Merge remote-tracking branch 'remotes/origin/master' into parallel_for

# Conflicts:
#	PERFORMANCE.md
#	lib/pls/CMakeLists.txt
#	lib/pls/include/pls/internal/scheduling/fork_join_task.h

CMakeLists.txt

@@ -34,11 +34,12 @@ add_subdirectory(app/playground)
 add_subdirectory(app/test_for_new)
 add_subdirectory(app/invoke_parallel)
 add_subdirectory(app/benchmark_fft)
+add_subdirectory(app/benchmark_unbalanced)
 
 # Add optional tests
 option(PACKAGE_TESTS "Build the tests" ON)
-if(PACKAGE_TESTS)
+if (PACKAGE_TESTS)
     enable_testing()
     add_subdirectory(test)
     add_test(NAME AllTests COMMAND tests)
-endif()
+endif ()

NOTES.md

@@ -4,6 +4,33 @@ A collection of stuff that we noticed during development.
 Useful later on two write a project report and to go back
 in time to find out why certain decisions where made.
 
+## 06.05.2019 - Relaxed Atomics
+
+At the end of the atomic talk it is mentioned how the relaxed
+atomics correspond to modern hardware, stating that starting with
+ARMv8 and x86 there is no real need for relaxed atomics,
+as the 'strict' ordering has no real performance impact.
+
+We will therefore ignore this for now (taking some potential
+performance hits on our banana pi m2 ARMv7 architecture),
+as it adds a lot of complexity and introduces many possibilities
+for subtle concurrency bugs.
+TODO: find some papers on the topic in case we want to mention
+it in our project report.
+
+## 06.05.2019 - Atomics
+
+Atomics are a big part to get lock-free code running and are also
+often useful for details like counters to spin on (e.g. is a task
+finished). Resources to understand them are found in
+[a talk online](https://herbsutter.com/2013/02/11/atomic-weapons-the-c-memory-model-and-modern-hardware/)
+and in the book 'C++ concurrency in action, Anthony Williams'.
+
+The key takeaway is that we need to be careful about ordering
+possibilities of variable reads/writes. We will start of to
+use strict ordering to begin with and will have to see if this
+impacts performance and if we need to optimize it.
+
 ## 12.04.2019 - Unique IDs
 
 Assigning unique IDs to logical different tasks is key to the

PERFORMANCE.md

@@ -63,3 +63,62 @@ to contemption, but could not resolve it with any combination
 of `tas_spinlock` vs `ttas_spinlock` and `lock` vs `try_lock`.
 
 This issue clearly needs further investigation.
+
+### Commit aa27064 - Performance with ttsa spinlocks (and 'full blocking' top level)
+
+<img src="media/aa27064_fft_average.png" width="400"/>
+
+### Commit d16ad3e - Performance with rw-lock and backoff
+
+<img src="media/d16ad3e_fft_average.png" width="400"/>
+
+### Commit 18b2d744 - Performance with lock-free deque
+
+After much tinkering we still have performance problems with higher
+thread counts in the FFT benchmark. Upward from 4/5 threads the
+performance gains start to saturate (before removing the top level
+locks we even saw a slight drop in performance).
+
+Currently the FFT benchmark shows the following results (average):
+
+<img src="media/18b2d744_fft_average.png" width="400"/>
+
+We want to positively note that the overall trend of 'performance drops'
+at the hyperthreading mark is not really bad anymore, it rather
+seems similar to EMBB now (with backoff + lockfree deque + top level
+reader-writers lock). This comes partly because the spike at 4 threads
+is lower (less performance at 4 threads). We also see better times
+on the multiprogramed system with the lock-free deque.
+
+This is discouraging after many tests. To see where the overhead lies
+we also implemented the unbalanced tree search benchmark,
+resulting in the following, suprisingly good, results (average):
+
+<img src="media/18b2d744_unbalanced_average.png" width="400"/>
+
+The main difference between the two benchmarks is, that the second
+one has more work and the work is relatively independent.
+Additionaly, the first one uses our high level API (parallel invoke),
+while the second one uses our low level API.
+It is worth investigating if either or high level API or the structure
+of the memory access in FFT are the problem.
+
+### Commit cf056856 - Remove two-level scheduler
+
+In this test we replace the two level scheduler with ONLY fork_join
+tasks. This removes the top level steal overhead and performs only
+internal stealing. For this we set the fork_join task as the only
+possible task type and removed the top level rw-lock, the digging
+down to our level and solely use internal stealing.
+
+Average results FFT:
+
+<img src="media/cf056856_fft_average.png" width="400"/>
+
+Average results Unbalanced:
+
+<img src="media/cf056856_unbalanced_average.png" width="400"/>
+
+There seems to be only a minor performance difference between the two,
+suggesting tha our two-level approach is not the part causing our
+weaker performance.

README.md

@@ -7,6 +7,8 @@
 
 This section will give a brief introduction on how to get a minimal
 project setup that uses the PLS library.
+Further [general notes](NOTES.md) and [performance notes](PERFORMANCE.md) can be found in
+their respective files.
 
 Further notes on [performance](PERFORMANCE.md) and general
 [notes](NOTES.md) on the development progress can be found in

app/benchmark_fft/main.cpp

@@ -6,9 +6,9 @@
 #include <complex>
 #include <vector>
 
-static constexpr int CUTOFF = 10;
+static constexpr int CUTOFF = 16;
 static constexpr int NUM_ITERATIONS = 1000;
-static constexpr int INPUT_SIZE = 2064;
+static constexpr int INPUT_SIZE = 8192;
 typedef std::vector<std::complex<double>> complex_vector;
 
 void divide(complex_vector::iterator data, int n) {
@@ -73,7 +73,6 @@ complex_vector prepare_input(int input_size) {
   return data;
 }
 
-
 int main() {
   PROFILE_ENABLE
   complex_vector initial_input = prepare_input(INPUT_SIZE);

app/benchmark_unbalanced/CMakeLists.txt

+add_executable(benchmark_unbalanced main.cpp node.h node.cpp picosha2.h)
+target_link_libraries(benchmark_unbalanced pls)
+if (EASY_PROFILER)
+    target_link_libraries(benchmark_unbalanced easy_profiler)
+endif ()

app/benchmark_unbalanced/LICENSE_PICOSA2

+MIT License
+
+Copyright (c) 2017 okdshin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file

app/benchmark_unbalanced/main.cpp

+#include <pls/pls.h>
+#include <pls/internal/helpers/profiler.h>
+#include <pls/internal/helpers/mini_benchmark.h>
+
+#include "node.h"
+
+const int SEED = 42;
+const int ROOT_CHILDREN = 140;
+const double Q = 0.124875;
+const int NORMAL_CHILDREN = 8;
+
+const int NUM_NODES = 71069;
+
+int count_child_nodes(uts::node &node) {
+  int child_count = 1;
+  std::vector<uts::node> children = node.spawn_child_nodes();
+
+  if (children.empty()) {
+    return child_count;
+  }
+
+  auto current_task = pls::fork_join_sub_task::current();
+  std::vector<int> results(children.size());
+  for (size_t i = 0; i < children.size(); i++) {
+    size_t index = i;
+    auto lambda = [&, index] { results[index] = count_child_nodes(children[index]); };
+    pls::fork_join_lambda_by_value<typeof(lambda)> sub_task(lambda);
+    current_task->spawn_child(sub_task);
+  }
+  current_task->wait_for_all();
+  for (auto result : results) {
+    child_count += result;
+  }
+
+  return child_count;
+}
+
+int unbalanced_tree_search(int seed, int root_children, double q, int normal_children) {
+  static auto id = pls::unique_id::create(42);
+  int result;
+
+  auto lambda = [&] {
+    uts::node root(seed, root_children, q, normal_children);
+    result = count_child_nodes(root);
+  };
+  pls::fork_join_lambda_by_reference<typeof(lambda)> task(lambda);
+  pls::fork_join_lambda_by_reference<typeof(lambda)> sub_task(lambda);
+  pls::fork_join_task root_task{&sub_task, id};
+  pls::scheduler::execute_task(root_task);
+
+  return result;
+}
+
+int main() {
+  PROFILE_ENABLE
+  pls::internal::helpers::run_mini_benchmark([&] {
+    unbalanced_tree_search(SEED, ROOT_CHILDREN, Q, NORMAL_CHILDREN);
+  }, 8, 4000);
+
+  PROFILE_SAVE("test_profile.prof")
+}
+
+//int main() {
+//  PROFILE_ENABLE
+//  pls::malloc_scheduler_memory my_scheduler_memory{8, 2u << 18};
+//  pls::scheduler scheduler{&my_scheduler_memory, 8};
+//
+//  scheduler.perform_work([&] {
+//    PROFILE_MAIN_THREAD
+//    for (int i = 0; i < 10; i++) {
+//      PROFILE_WORK_BLOCK("Top Level")
+//      int result = unbalanced_tree_search(SEED, ROOT_CHILDREN, Q, NORMAL_CHILDREN);
+//      std::cout << result << std::endl;
+//    }
+//  });
+//
+//  PROFILE_SAVE("test_profile.prof")
+//}

app/benchmark_unbalanced/node.cpp

+#include "node.h"
+
+namespace uts {
+node_state node::generate_child_state(uint32_t index) {
+  node_state result;
+
+  picosha2::hash256_one_by_one hasher;
+  hasher.process(state_.begin(), state_.end());
+  auto index_begin = reinterpret_cast<uint8_t *>(&index);
+  hasher.process(index_begin, index_begin + 4);
+  hasher.finish();
+  hasher.get_hash_bytes(result.begin(), result.end());
+
+  return result;
+}
+
+double node::get_state_random() {
+  int32_t state_random_integer;
+  uint32_t b = ((uint32_t) state_[16] << 24) |
+      ((uint32_t) state_[17] << 16) |
+      ((uint32_t) state_[18] << 8) |
+      ((uint32_t) state_[19] << 0);
+  b = b & 0x7fffffff; // Mask out negative values
+  state_random_integer = static_cast<int32_t>(b);
+
+  return (double) state_random_integer / (double) INT32_MAX;
+}
+}

app/benchmark_unbalanced/node.h

+
+#ifndef UTS_NODE_H
+#define UTS_NODE_H
+
+#include <cstdint>
+#include <array>
+#include <vector>
+
+#include "picosha2.h"
+
+namespace uts {
+using node_state = std::array<uint8_t, 20>;
+
+/**
+ * Node of an unballanced binomial tree (https://www.cs.unc.edu/~olivier/LCPC06.pdf).
+ * To build up the tree recursivly call spawn_child_nodes on each node until leaves are reached.
+ * The tree is not built up directly in memory, but rather by the recursive calls.
+ */
+class node {
+  // The state is used to allow a deterministic tree construction using sha256 hashes.
+  node_state state_;
+
+  // Set this to a positive number for the root node to start the tree with a specific size
+  int root_children_;
+
+  // general branching factors
+  double q_;
+  int b_;
+
+  // Private constructor for children
+  node(node_state state, double q, int b) : state_{state}, root_children_{-1}, q_{q}, b_{b} {}
+
+  std::array<uint8_t, 20> generate_child_state(uint32_t index);
+  double get_state_random();
+
+ public:
+  node(int seed, int root_children, double q, int b) : state_({{}}), root_children_{root_children}, q_{q}, b_{b} {
+    for (int i = 0; i < 16; i++) {
+      state_[i] = 0;
+    }
+    state_[16] = static_cast<uint8_t>(0xFF & (seed >> 24));
+    state_[17] = static_cast<uint8_t>(0xFF & (seed >> 16));
+    state_[18] = static_cast<uint8_t>(0xFF & (seed >> 8));
+    state_[19] = static_cast<uint8_t>(0xFF & (seed >> 0));
+
+    picosha2::hash256_one_by_one hasher;
+    hasher.process(state_.begin(), state_.end());
+    hasher.finish();
+    hasher.get_hash_bytes(state_.begin(), state_.end());
+  }
+
+  std::vector<node> spawn_child_nodes() {
+    double state_random = get_state_random();
+    int num_children;
+    if (root_children_ > 0) {
+      num_children = root_children_; // Root always spawns children
+    } else if (state_random < q_) {
+      num_children = b_;
+    } else {
+      num_children = 0;
+    }
+
+    std::vector<node> result;
+    for (int i = 0; i < num_children; i++) {
+      result.push_back(node(generate_child_state(i), q_, b_));
+    }
+
+    return result;
+  }
+};
+}
+
+#endif //UTS_NODE_H

app/invoke_parallel/main.cpp

@@ -2,48 +2,99 @@
 #include <pls/internal/helpers/profiler.h>
 
 #include <iostream>
+#include <complex>
+#include <vector>
 
-static pls::static_scheduler_memory<8, 2 << 14> my_scheduler_memory;
+static constexpr int CUTOFF = 16;
+static constexpr int INPUT_SIZE = 8192;
+typedef std::vector<std::complex<double>> complex_vector;
 
-static constexpr int CUTOFF = 10;
-
-long fib_serial(long n) {
-    if (n == 0) {
-        return 0;
+void divide(complex_vector::iterator data, int n) {
+  complex_vector tmp_odd_elements(n / 2);
+  for (int i = 0; i < n / 2; i++) {
+    tmp_odd_elements[i] = data[i * 2 + 1];
+  }
+  for (int i = 0; i < n / 2; i++) {
+    data[i] = data[i * 2];
   }
-    if (n == 1) {
-        return 1;
+  for (int i = 0; i < n / 2; i++) {
+    data[i + n / 2] = tmp_odd_elements[i];
   }
+}
+
+void combine(complex_vector::iterator data, int n) {
+  for (int i = 0; i < n / 2; i++) {
+    std::complex<double> even = data[i];
+    std::complex<double> odd = data[i + n / 2];
 
-    return fib_serial(n - 1) + fib_serial(n - 2);
+    // w is the "twiddle-factor".
+    // this could be cached, but we run the same 'data_structures' algorithm parallel/serial,
+    // so it won't impact the performance comparison.
+    std::complex<double> w = exp(std::complex<double>(0, -2. * M_PI * i / n));
+
+    data[i] = even + w * odd;
+    data[i + n / 2] = even - w * odd;
+  }
 }
 
-long fib(long n) {
-    if (n <= CUTOFF) {
-        return fib_serial(n);
+void fft(complex_vector::iterator data, int n) {
+  if (n < 2) {
+    return;
   }
 
-    // Actual 'invoke_parallel' logic/code
-    int left, right;
+  PROFILE_WORK_BLOCK("Divide")
+  divide(data, n);
+  PROFILE_END_BLOCK
+  PROFILE_WORK_BLOCK("Invoke Parallel")
+  if (n == CUTOFF) {
+    PROFILE_WORK_BLOCK("FFT Serial")
+    fft(data, n / 2);
+    fft(data + n / 2, n / 2);
+  } else if (n <= CUTOFF) {
+    fft(data, n / 2);
+    fft(data + n / 2, n / 2);
+  } else {
     pls::invoke_parallel(
-        [&] { left = fib(n - 1); },
-        [&] { right = fib(n - 2); }
+        [&] { fft(data, n / 2); },
+        [&] { fft(data + n / 2, n / 2); }
     );
-    return left + right;
+  }
+  PROFILE_END_BLOCK
+  PROFILE_WORK_BLOCK("Combine")
+  combine(data, n);
+  PROFILE_END_BLOCK
+}
+
+complex_vector prepare_input(int input_size) {
+  std::vector<double> known_frequencies{2, 11, 52, 88, 256};
+  complex_vector data(input_size);
+
+  // Set our input data to match a time series of the known_frequencies.
+  // When applying fft to this time-series we should find these frequencies.
+  for (int i = 0; i < input_size; i++) {
+    data[i] = std::complex<double>(0.0, 0.0);
+    for (auto frequencie : known_frequencies) {
+      data[i] += sin(2 * M_PI * frequencie * i / input_size);
+    }
+  }
+
+  return data;
 }
 
 int main() {
   PROFILE_ENABLE
+  pls::malloc_scheduler_memory my_scheduler_memory{8, 2u << 14};
   pls::scheduler scheduler{&my_scheduler_memory, 8};
 
-    long result;
+  complex_vector initial_input = prepare_input(INPUT_SIZE);
   scheduler.perform_work([&] {
     PROFILE_MAIN_THREAD
     // Call looks just the same, only requirement is
     // the enclosure in the perform_work lambda.
     for (int i = 0; i < 10; i++) {
-            result = fib(30);
-            std::cout << "Fib(30)=" << result << std::endl;
+      PROFILE_WORK_BLOCK("Top Level FFT")
+      complex_vector input = initial_input;
+      fft(input.begin(), input.size());
     }
   });
 

app/playground/main.cpp

@@ -10,8 +10,6 @@
 #include <pls/internal/scheduling/root_task.h>
 #include <pls/internal/helpers/unique_id.h>
 
-
 int main() {
-    std::cout << pls::internal::scheduling::root_task<void(*)>::create_id().type_.hash_code() << std::endl;
-    std::cout << pls::internal::helpers::unique_id::create<pls::internal::scheduling::root_task<void(*)>>().type_.hash_code() << std::endl;
+
 }

app/test_for_new/main.cpp

@@ -5,9 +5,8 @@ using namespace pls::internal::base;
 
 int global = 0;
 
-
 int main() {
   // Try to use every feature, to trigger the prohibited use of new if found somewhere
-    auto t1 = start_thread([] (){});
+  auto t1 = start_thread([]() {});
   t1.join();
 }

lib/pls/include/pls/algorithms/invoke_parallel.h

@@ -6,15 +6,17 @@
 #include "pls/internal/scheduling/scheduler.h"
 
 namespace pls {
-    namespace algorithm {
-        template<typename Function1, typename Function2>
-        void invoke_parallel(const Function1& function1, const Function2& function2);
+namespace algorithm {
 
-        template<typename Function1, typename Function2, typename Function3>
-        void invoke_parallel(const Function1& function1, const Function2& function2, const Function3& function3);
+template<typename Function1, typename Function2>
+void invoke_parallel(const Function1 &function1, const Function2 &function2);
 
-        // ...and so on, add more if we decide to keep this design
-    }
+template<typename Function1, typename Function2, typename Function3>
+void invoke_parallel(const Function1 &function1, const Function2 &function2, const Function3 &function3);
+
+// ...and so on, add more if we decide to keep this design
+
+}
 }
 #include "invoke_parallel_impl.h"
 

lib/pls/include/pls/algorithms/invoke_parallel_impl.h

@@ -2,70 +2,73 @@
 #ifndef PLS_INVOKE_PARALLEL_IMPL_H
 #define PLS_INVOKE_PARALLEL_IMPL_H
 
+#include <pls/internal/scheduling/fork_join_task.h>
 #include "pls/internal/scheduling/fork_join_task.h"
 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/helpers/unique_id.h"
+#include "pls/internal/base/alignment.h"
 
 namespace pls {
-    namespace algorithm {
-        namespace internal {
-            using namespace ::pls::internal::scheduling;
+namespace algorithm {
+namespace internal {
+
+using namespace ::pls::internal::scheduling;
 
-            template<typename Body>
-            inline void run_body(const Body& internal_body, const abstract_task::id& id) {
+template<typename Body>
+inline void run_body(const Body &internal_body, const abstract_task::id &id) {
   // Make sure we are in the context of this invoke_parallel instance,
   // if not we will spawn it as a new 'fork-join-style' task.
   auto current_task = scheduler::current_task();
   if (current_task->unique_id() == id) {
-                    auto current_sub_task = reinterpret_cast<fork_join_task*>(current_task)->currently_executing();
-                    internal_body(current_sub_task);
+    internal_body();
   } else {
-                    fork_join_lambda<Body> root_body(&internal_body);
+    fork_join_lambda_by_reference<Body> root_body(internal_body);
     fork_join_task root_task{&root_body, id};
     scheduler::execute_task(root_task);
   }
-            }
-        }
+}
+}
 
-        template<typename Function1, typename Function2>
-        void invoke_parallel(const Function1& function1, const Function2& function2) {
+template<typename Function1, typename Function2>
+void invoke_parallel(const Function1 &function1, const Function2 &function2) {
   using namespace ::pls::internal::scheduling;
   using namespace ::pls::internal::helpers;
+  using namespace ::pls::internal::base;
   static abstract_task::id id = unique_id::create<Function1, Function2>();
 
-            auto internal_body = [&] (fork_join_sub_task* this_task){
-                auto sub_task_body_1 = [&] (fork_join_sub_task*){ function1(); };
-                auto sub_task_1 = fork_join_lambda<decltype(sub_task_body_1)>(&sub_task_body_1);
+  auto internal_body = [&]() {
+    auto current_task = fork_join_sub_task::current();
+    auto sub_task_2 = fork_join_lambda_by_reference<Function2>(function2);
 
-                this_task->spawn_child(sub_task_1);
-                function2(); // Execute last function 'inline' without spawning a sub_task object
-                this_task->wait_for_all();
+    current_task->spawn_child(sub_task_2);
+    function1(); // Execute first function 'inline' without spawning a sub_task object
+    current_task->wait_for_all();
   };
 
   internal::run_body(internal_body, id);
-        }
+}
 
-        template<typename Function1, typename Function2, typename Function3>
-        void invoke_parallel(const Function1& function1, const Function2& function2, const Function3& function3) {
+template<typename Function1, typename Function2, typename Function3>
+void invoke_parallel(const Function1 &function1, const Function2 &function2, const Function3 &function3) {
   using namespace ::pls::internal::scheduling;
   using namespace ::pls::internal::helpers;
   static abstract_task::id id = unique_id::create<Function1, Function2, Function3>();
 
-            auto internal_body = [&] (fork_join_sub_task* this_task){
-                auto sub_task_body_1 = [&] (fork_join_sub_task*){ function1(); };
-                auto sub_task_1 = fork_join_lambda<decltype(sub_task_body_1)>(&sub_task_body_1);
-                auto sub_task_body_2 = [&] (fork_join_sub_task*){ function2(); };
-                auto sub_task_2 = fork_join_lambda<decltype(sub_task_body_2)>(&sub_task_body_2);
+  auto internal_body = [&]() {
+    auto current_task = fork_join_sub_task::current();
+    auto sub_task_2 = fork_join_lambda_by_reference<Function2>(function2);
+    auto sub_task_3 = fork_join_lambda_by_reference<Function3>(function3);
 
-                this_task->spawn_child(sub_task_1);
-                this_task->spawn_child(sub_task_2);
-                function3(); // Execute last function 'inline' without spawning a sub_task object
-                this_task->wait_for_all();
+    current_task->spawn_child(sub_task_2);
+    current_task->spawn_child(sub_task_3);
+    function1(); // Execute first function 'inline' without spawning a sub_task object
+    current_task->wait_for_all();
   };
 
   internal::run_body(internal_body, id);
-        }
-    }
+}
+
+}
 }
 
 #endif //PLS_INVOKE_PARALLEL_IMPL_H

lib/pls/include/pls/internal/base/alignment.h

@@ -8,21 +8,45 @@
 #include "system_details.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            namespace alignment {
-                template<typename T>
-                struct aligned_wrapper {
+namespace internal {
+namespace base {
+namespace alignment {
+
+template<typename T>
+struct aligned_wrapper {
   alignas(system_details::CACHE_LINE_SIZE) unsigned char data[sizeof(T)];
-                    T* pointer() { return reinterpret_cast<T*>(data); }
-                };
-                void* allocate_aligned(size_t size);
+  T *pointer() { return reinterpret_cast<T *>(data); }
+};
+void *allocate_aligned(size_t size);
+
+system_details::pointer_t next_alignment(system_details::pointer_t size);
+system_details::pointer_t previous_alignment(system_details::pointer_t size);
+char *next_alignment(char *pointer);
+
+}
+
+template<typename T>
+struct aligned_aba_pointer {
+  const system_details::pointer_t pointer_;
+
+  explicit aligned_aba_pointer(T *pointer, unsigned int aba = 0) : pointer_{
+      reinterpret_cast<system_details::pointer_t >(pointer) + aba} {}
 
-                std::uintptr_t next_alignment(std::uintptr_t size);
-                char* next_alignment(char* pointer);
+  T *pointer() const {
+    return reinterpret_cast<T *>(pointer_ & system_details::CACHE_LINE_ADDRESS_USED_BITS);
   }
+
+  unsigned int aba() const {
+    return pointer_ & system_details::CACHE_LINE_ADDRESS_UNUSED_BITS;
   }
+
+  aligned_aba_pointer set_aba(unsigned int aba) const {
+    return aligned_aba_pointer(pointer(), aba);
   }
+};
+
+}
+}
 }
 
 #endif //PLS_ALIGNMENT_H

lib/pls/include/pls/internal/base/backoff.h

+
+#ifndef PLS_BACKOFF_H_
+#define PLS_BACKOFF_H_
+
+#include "pls/internal/base/system_details.h"
+#include "pls/internal/helpers/profiler.h"
+#include "pls/internal/base/thread.h"
+
+#include <random>
+#include <math.h>
+
+namespace pls {
+namespace internal {
+namespace base {
+
+class backoff {
+  const unsigned long INITIAL_SPIN_ITERS = 2u << 4u;
+  const unsigned long MAX_SPIN_ITERS = 2u << 8u;
+  const unsigned long MAX_ITERS = 2u << 10u;
+  const unsigned long YELD_ITERS = 2u << 10u;
+
+  unsigned long current_ = INITIAL_SPIN_ITERS;
+  std::minstd_rand random_;
+
+  static void spin(unsigned long iterations) {
+    for (volatile unsigned long i = 0; i < iterations; i++)
+      system_details::relax_cpu(); // Spin
+  }
+
+ public:
+  backoff() : current_{INITIAL_SPIN_ITERS}, random_{std::random_device{}()} {}
+
+  void do_backoff() {
+    PROFILE_LOCK("Backoff")
+    spin(random_() % std::min(current_, MAX_SPIN_ITERS));
+
+    if (current_ >= YELD_ITERS) {
+      PROFILE_LOCK("Yield")
+      this_thread::yield();
+    }
+
+    current_ = std::min(current_ * 2, MAX_ITERS);
+  }
+
+  void reset() {
+    current_ = INITIAL_SPIN_ITERS;
+  }
+};
+
+}
+}
+}
+
+#endif //PLS_BACKOFF_H_

lib/pls/include/pls/internal/base/barrier.h

@@ -5,9 +5,10 @@
 #include <pthread.h>
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
+namespace internal {
+namespace base {
+
+/**
  * Provides standard barrier behaviour.
  * `count` threads have to call `wait()` before any of the `wait()` calls returns,
  * thus blocking all threads until everyone reached the barrier.
@@ -15,7 +16,7 @@ namespace pls {
  * PORTABILITY:
  * Current implementation is based on pthreads.
  */
-            class barrier {
+class barrier {
   pthread_barrier_t barrier_;
 
  public:
@@ -23,9 +24,10 @@ namespace pls {
   ~barrier();
 
   void wait();
-            };
-        }
-    }
+};
+
+}
+}
 }
 
 #endif //PLS_BARRIER_H

lib/pls/include/pls/internal/base/error_handling.h

@@ -11,5 +11,6 @@
  * (or its inclusion adds too much overhead).
  */
 #define PLS_ERROR(msg) std::cout << msg << std::endl; exit(1);
+#define PLS_ASSERT(cond, msg) if (!cond) { PLS_ERROR(msg) }
 
 #endif //PLS_ERROR_HANDLING_H

lib/pls/include/pls/internal/base/spin_lock.h

@@ -6,12 +6,14 @@
 #include "ttas_spin_lock.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            // Default Spin-Lock implementation for this project.
-            using spin_lock = tas_spin_lock;
-        }
-    }
+namespace internal {
+namespace base {
+
+// Default Spin-Lock implementation for this project.
+using spin_lock = ttas_spin_lock;
+
+}
+}
 }
 
 #endif //PLS_SPINLOCK_H

lib/pls/include/pls/internal/base/swmr_spin_lock.h

+
+#ifndef PLS_SWMR_SPIN_LOCK_LOCK_H_
+#define PLS_SWMR_SPIN_LOCK_LOCK_H_
+
+#include <atomic>
+
+#include "pls/internal/helpers/profiler.h"
+
+namespace pls {
+namespace internal {
+namespace base {
+
+/**
+ * Single writer, multiple reader spin lock.
+ * The writer is required to be the same thread all the time (single writer),
+ * while multiple threads can read.
+ * Readers fail to lock when the writer requests the lock,
+ * the acquires the lock after all remaining readers left the critical section.
+ */
+class swmr_spin_lock {
+  std::atomic<int> readers_;
+  std::atomic<int> write_request_;
+
+ public:
+  explicit swmr_spin_lock() : readers_{0}, write_request_{0} {}
+
+  bool reader_try_lock();
+  void reader_unlock();
+
+  void writer_lock();
+  void writer_unlock();
+};
+
+}
+}
+}
+
+#endif //PLS_SWMR_SPIN_LOCK_LOCK_H_

lib/pls/include/pls/internal/base/system_details.h

@@ -3,31 +3,76 @@
 #define PLS_SYSTEM_DETAILS_H
 
 #include <cstdint>
+#if (COMPILER == MVCC)
+#include <emmintrin.h>
+#endif
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
+namespace internal {
+namespace base {
+
+/**
  * Collection of system details, e.g. hardware cache line size.
  *
  * PORTABILITY:
  * Currently sane default values for x86.
  */
-            namespace system_details {
-                /**
-                 * Most processors have 64 byte cache lines
+namespace system_details {
+
+/**
+ * Pointer Types needed for ABA protection mixed into addresses.
+ * pointer_t should be an integer type capable of holding ANY pointer value.
+ */
+using pointer_t = std::uintptr_t;
+constexpr pointer_t ZERO_POINTER = 0;
+constexpr pointer_t MAX_POINTER = ~ZERO_POINTER;
+
+/**
+ * Biggest type that supports atomic CAS operations.
+ * Usually it is sane to assume a pointer can be swapped in a single CAS operation.
+ */
+using cas_integer = pointer_t;
+constexpr cas_integer MIN_CAS_INTEGER = 0;
+constexpr cas_integer MAX_CAS_INTEGER = ~MIN_CAS_INTEGER;
+constexpr cas_integer FIRST_HALF_CAS_INTEGER = MAX_CAS_INTEGER << ((sizeof(cas_integer) / 2) * 8);
+constexpr cas_integer SECOND_HALF_CAS_INTEGER = ~FIRST_HALF_CAS_INTEGER;
+
+/**
+ * Most processors have 64 byte cache lines (last 6 bit of the address are zero at line beginnings).
  */
-                constexpr std::uintptr_t CACHE_LINE_SIZE = 64;
+constexpr unsigned int CACHE_LINE_ADDRESS_BITS = 6;
+constexpr pointer_t CACHE_LINE_SIZE = 2u << (CACHE_LINE_ADDRESS_BITS - 1);
+constexpr pointer_t CACHE_LINE_ADDRESS_USED_BITS = MAX_POINTER << CACHE_LINE_ADDRESS_BITS;
+constexpr pointer_t CACHE_LINE_ADDRESS_UNUSED_BITS = ~CACHE_LINE_ADDRESS_USED_BITS;
 
-                /**
+/**
  * Choose one of the following ways to store thread specific data.
  * Try to choose the fastest available on this processor/system.
  */
-//                #define PLS_THREAD_SPECIFIC_PTHREAD
-                #define PLS_THREAD_SPECIFIC_COMPILER
-            }
-        }
-    }
+//#define PLS_THREAD_SPECIFIC_PTHREAD
+#define PLS_THREAD_SPECIFIC_COMPILER
+
+/**
+ * When spinning one wants to 'relax' the CPU from some task,
+ * e.g. disabling speculative execution/branch prediction
+ * or reducing its clock speed.
+ * This is both good for power draw, as well as for hyperthreading.
+ *
+ * Choose the implementation appropriate for your compiler-cpu combination.
+ */
+#if (COMPILER == MVCC)
+inline void relax_cpu() {
+  _mm_pause();
+}
+#elif (COMPILER == GCC || COMPILER == LLVM)
+inline void relax_cpu() {
+  asm("pause");
+}
+#endif
+
+}
+}
+}
 }
 
 #endif //PLS_SYSTEM_DETAILS_H

lib/pls/include/pls/internal/base/tas_spin_lock.h

@@ -10,30 +10,29 @@
 #include "pls/internal/base/thread.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
+namespace internal {
+namespace base {
+
+/**
  * A simple set and test_and_set based spin lock implementation.
  *
  * PORTABILITY:
  * Current implementation is based on C++ 11 atomic_flag.
  */
-            class tas_spin_lock {
+class tas_spin_lock {
   std::atomic_flag flag_;
-                unsigned int yield_at_tries_;
-
 
  public:
-                tas_spin_lock(): flag_{ATOMIC_FLAG_INIT}, yield_at_tries_{1024} {};
-                tas_spin_lock(const tas_spin_lock& other): flag_{ATOMIC_FLAG_INIT}, yield_at_tries_{other.yield_at_tries_} {}
+  tas_spin_lock() : flag_{ATOMIC_FLAG_INIT} {};
+  tas_spin_lock(const tas_spin_lock &/*other*/) : flag_{ATOMIC_FLAG_INIT} {}
 
   void lock();
-                bool try_lock(unsigned int num_tries=1);
+  bool try_lock(unsigned int num_tries = 1);
   void unlock();
-            };
-        }
-    }
-}
+};
 
+}
+}
+}
 
 #endif //PLS_TAS_SPIN_LOCK_H

lib/pls/include/pls/internal/base/thread.h

@@ -9,15 +9,17 @@
 #include <functional>
 #include <pthread.h>
 #include <atomic>
+#include <time.h>
 
 #include "system_details.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            using thread_entrypoint = void();
+namespace internal {
+namespace base {
 
-            /**
+using thread_entrypoint = void();
+
+/**
  * Static methods than can be performed on the current thread.
  *
  * usage:
@@ -27,21 +29,27 @@ namespace pls {
  * PORTABILITY:
  * Current implementation is based on pthreads.
  */
-            class this_thread {
+class this_thread {
   template<typename Function, typename State>
-                friend class thread;
+  friend
+  class thread;
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
   static pthread_key_t local_storage_key_;
   static bool local_storage_key_initialized_;
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-                static __thread void* local_state_;
+  static __thread void *local_state_;
 #endif
  public:
   static void yield() {
     pthread_yield();
   }
 
+  static void sleep(long microseconds) {
+    timespec time{0, 1000 * microseconds};
+    nanosleep(&time, nullptr);
+  }
+
   /**
    * Retrieves the local state pointer.
    *
@@ -49,7 +57,7 @@ namespace pls {
    * @return The state pointer hold for this thread.
    */
   template<typename T>
-                static T* state();
+  static T *state();
 
   /**
    * Stores a pointer to the thread local state object.
@@ -60,10 +68,10 @@ namespace pls {
    * @param state_pointer A pointer to the threads state object.
    */
   template<typename T>
-                static void set_state(T* state_pointer);
-            };
+  static void set_state(T *state_pointer);
+};
 
-            /**
+/**
  * Abstraction for starting a function in a separate thread.
  *
  * @tparam Function Lambda being started on the new thread.
@@ -79,43 +87,44 @@ namespace pls {
  * PORTABILITY:
  * Current implementation is based on pthreads.
  */
-            template<typename Function, typename State>
-            class thread {
+template<typename Function, typename State>
+class thread {
   friend class this_thread;
   // Keep a copy of the function (lambda) in this object to make sure it is valid when called!
   Function function_;
-                State* state_pointer_;
+  State *state_pointer_;
 
   // Wee need to wait for the started function to read
   // the function_ and state_pointer_ property before returning
   // from the constructor, as the object might be moved after this.
-                std::atomic_flag* startup_flag_;
+  std::atomic_flag *startup_flag_;
 
   // Keep handle to native implementation
   pthread_t pthread_thread_;
 
-                static void* start_pthread_internal(void* thread_pointer);
+  static void *start_pthread_internal(void *thread_pointer);
 
  public:
-                explicit thread(const Function& function, State* state_pointer);
+  explicit thread(const Function &function, State *state_pointer);
 
  public:
   void join();
 
   // make object move only
-                thread(thread&&) noexcept = default;
-                thread& operator=(thread&&) noexcept = default;
+  thread(thread &&) noexcept = default;
+  thread &operator=(thread &&) noexcept = default;
 
-                thread(const thread&) = delete;
-                thread& operator=(const thread&) = delete;
-            };
+  thread(const thread &) = delete;
+  thread &operator=(const thread &) = delete;
+};
 
-            template<typename Function, typename State>
-            thread<Function, State> start_thread(const Function& function, State* state_pointer);
-            template<typename Function>
-            thread<Function, void> start_thread(const Function& function);
-        }
-    }
+template<typename Function, typename State>
+thread<Function, State> start_thread(const Function &function, State *state_pointer);
+template<typename Function>
+thread<Function, void> start_thread(const Function &function);
+
+}
+}
 }
 #include "thread_impl.h"
 

lib/pls/include/pls/internal/base/thread_impl.h

@@ -3,33 +3,34 @@
 #define PLS_THREAD_IMPL_H
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            template<typename T>
-            T* this_thread::state() {
+namespace internal {
+namespace base {
+
+template<typename T>
+T *this_thread::state() {
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
   return reinterpret_cast<T*>(pthread_getspecific(local_storage_key_));
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-                return reinterpret_cast<T*>(local_state_);
+  return reinterpret_cast<T *>(local_state_);
 #endif
-            }
+}
 
-            template<typename T>
-            void this_thread::set_state(T* state_pointer) {
+template<typename T>
+void this_thread::set_state(T *state_pointer) {
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
   pthread_setspecific(this_thread::local_storage_key_, (void*)state_pointer);
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
   local_state_ = state_pointer;
 #endif
-            }
+}
 
-            template<typename Function, typename State>
-            void* thread<Function, State>::start_pthread_internal(void* thread_pointer) {
-                auto my_thread = reinterpret_cast<thread*>(thread_pointer);
+template<typename Function, typename State>
+void *thread<Function, State>::start_pthread_internal(void *thread_pointer) {
+  auto my_thread = reinterpret_cast<thread *>(thread_pointer);
   Function my_function_copy = my_thread->function_;
-                State* my_state_pointer_copy = my_thread->state_pointer_;
+  State *my_state_pointer_copy = my_thread->state_pointer_;
 
   // Now we have copies of everything we need on the stack.
   // The original thread object can be moved freely (no more
@@ -41,10 +42,10 @@ namespace pls {
 
   // Finished executing the user function
   pthread_exit(nullptr);
-            }
+}
 
-            template<typename Function, typename State>
-            thread<Function, State>::thread(const Function& function, State* state_pointer):
+template<typename Function, typename State>
+thread<Function, State>::thread(const Function &function, State *state_pointer):
     function_{function},
     state_pointer_{state_pointer},
     startup_flag_{nullptr},
@@ -62,27 +63,27 @@ namespace pls {
   startup_flag_ = &startup_flag;
 
   startup_flag.test_and_set(); // Set the flag, pthread will clear it when it is safe to return
-                pthread_create(&pthread_thread_, nullptr, start_pthread_internal, (void *)(this));
-                while (startup_flag.test_and_set())
-                    ; // Busy waiting for the starting flag to clear
-            }
+  pthread_create(&pthread_thread_, nullptr, start_pthread_internal, (void *) (this));
+  while (startup_flag.test_and_set()); // Busy waiting for the starting flag to clear
+}
 
-            template<typename Function, typename State>
-            void thread<Function, State>::join() {
+template<typename Function, typename State>
+void thread<Function, State>::join() {
   pthread_join(pthread_thread_, nullptr);
-            }
+}
 
-            template<typename Function, typename State>
-            thread<Function, State> start_thread(const Function& function, State* state_pointer) {
+template<typename Function, typename State>
+thread<Function, State> start_thread(const Function &function, State *state_pointer) {
   return thread<Function, State>(function, state_pointer);
-            }
+}
 
-            template<typename Function>
-            thread<Function, void> start_thread(const Function& function) {
+template<typename Function>
+thread<Function, void> start_thread(const Function &function) {
   return thread<Function, void>(function, nullptr);
-            }
-        }
-    }
+}
+
+}
+}
 }
 
 #endif //PLS_THREAD_IMPL_H

lib/pls/include/pls/internal/base/ttas_spin_lock.h

@@ -6,32 +6,30 @@
 #include <iostream>
 
 #include "pls/internal/base/thread.h"
+#include "pls/internal/base/backoff.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
+namespace internal {
+namespace base {
+/**
  * A simple set and test_and_set based spin lock implementation.
  *
  * PORTABILITY:
  * Current implementation is based on C++ 11 atomic_flag.
  */
-            class ttas_spin_lock {
+class ttas_spin_lock {
   std::atomic<int> flag_;
-                const unsigned int yield_at_tries_;
-
 
  public:
-                ttas_spin_lock(): flag_{0}, yield_at_tries_{1024} {};
-                ttas_spin_lock(const ttas_spin_lock& other): flag_{0}, yield_at_tries_{other.yield_at_tries_} {}
+  ttas_spin_lock() : flag_{0} {};
+  ttas_spin_lock(const ttas_spin_lock &/*other*/) : flag_{0} {}
 
   void lock();
-                bool try_lock(unsigned int num_tries=1);
+  bool try_lock(unsigned int num_tries = 1);
   void unlock();
-            };
-        }
-    }
+};
+}
+}
 }
-
 
 #endif //PLS_TTAS_SPIN_LOCK_H

lib/pls/include/pls/internal/data_structures/aligned_stack.h

@@ -9,9 +9,12 @@
 #include "pls/internal/base/alignment.h"
 
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            /**
+namespace internal {
+namespace data_structures {
+
+using base::system_details::pointer_t;
+
+/**
  * Generic stack-like data structure that allows to allocate arbitrary objects in a given memory region.
  * The objects will be stored aligned in the stack, making the storage cache friendly and very fast
  * (as long as one can live with the stack restrictions).
@@ -23,31 +26,33 @@ namespace pls {
  * T* pointer = stack.push(some_object); // Copy-Constrict the object on top of stack
  * stack.pop<T>(); // Deconstruct the top object of type T
  */
-            class aligned_stack {
+class aligned_stack {
   // Keep bounds of our memory block
-                char* memory_start_;
-                char* memory_end_;
+  pointer_t memory_start_;
+  pointer_t memory_end_;
 
   // Current head will always be aligned to cache lines
-                char* head_;
+  pointer_t head_;
  public:
-                typedef char* state;
+  typedef pointer_t state;
 
-                aligned_stack(): memory_start_{nullptr}, memory_end_{nullptr}, head_{nullptr} {};
-                aligned_stack(char* memory_region, std::size_t size);
+  aligned_stack() : memory_start_{0}, memory_end_{0}, head_{0} {};
+  aligned_stack(pointer_t memory_region, std::size_t size);
+  aligned_stack(char *memory_region, std::size_t size);
 
   template<typename T>
-                T* push(const T& object);
+  T *push(const T &object);
   template<typename T>
-                void* push();
+  void *push();
   template<typename T>
   T pop();
 
   state save_state() const { return head_; }
   void reset_state(state new_state) { head_ = new_state; }
-            };
-        }
-    }
+};
+
+}
+}
 }
 #include "aligned_stack_impl.h"
 

lib/pls/include/pls/internal/data_structures/aligned_stack_impl.h

@@ -3,17 +3,18 @@
 #define PLS_ALIGNED_STACK_IMPL_H
 
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            template<typename T>
-            T* aligned_stack::push(const T& object) {
+namespace internal {
+namespace data_structures {
+
+template<typename T>
+T *aligned_stack::push(const T &object) {
   // Copy-Construct
-                return new ((void*)push<T>())T(object);
-            }
+  return new(push < T > ())T(object);
+}
 
-            template<typename T>
-            void* aligned_stack::push() {
-                void* result = reinterpret_cast<T*>(head_);
+template<typename T>
+void *aligned_stack::push() {
+  void *result = reinterpret_cast<T *>(head_);
 
   // Move head to next aligned position after new object
   head_ = base::alignment::next_alignment(head_ + sizeof(T));
@@ -22,15 +23,16 @@ namespace pls {
   }
 
   return result;
-            }
+}
 
-            template<typename T>
-            T aligned_stack::pop() {
+template<typename T>
+T aligned_stack::pop() {
   head_ = head_ - base::alignment::next_alignment(sizeof(T));
-                return *reinterpret_cast<T*>(head_);
-            }
-        }
-    }
+  return *reinterpret_cast<T *>(head_);
+}
+
+}
+}
 }
 
 #endif //PLS_ALIGNED_STACK_IMPL_H

lib/pls/include/pls/internal/data_structures/deque.h

@@ -5,56 +5,58 @@
 #include "pls/internal/base/spin_lock.h"
 
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            /**
+namespace internal {
+namespace data_structures {
+
+/**
  * Turns any object into deque item when inheriting from this.
  */
-            class deque_item {
+class deque_item {
   friend class deque_internal;
 
-                deque_item* prev_;
-                deque_item* next_;
+  deque_item *prev_;
+  deque_item *next_;
 
-            };
+};
 
-            class deque_internal {
+class deque_internal {
  protected:
-                deque_item* head_;
-                deque_item* tail_;
+  deque_item *head_;
+  deque_item *tail_;
 
   base::spin_lock lock_;
 
-                deque_item* pop_head_internal();
-                deque_item* pop_tail_internal();
+  deque_item *pop_head_internal();
+  deque_item *pop_tail_internal();
   void push_tail_internal(deque_item *new_item);
-            };
+};
 
-            /**
+/**
  * A double linked list based deque.
  * Storage is therefore only needed for the individual items.
  *
  * @tparam Item The type of items stored in this deque
  */
-            template<typename Item>
-            class deque: deque_internal {
+template<typename Item>
+class deque : deque_internal {
  public:
-                explicit deque(): deque_internal{} {}
+  explicit deque() : deque_internal{} {}
 
-                inline Item* pop_head() {
-                    return static_cast<Item*>(pop_head_internal());
+  inline Item *pop_head() {
+    return static_cast<Item *>(pop_head_internal());
   }
 
-                inline Item* pop_tail() {
-                    return static_cast<Item*>(pop_tail_internal());
+  inline Item *pop_tail() {
+    return static_cast<Item *>(pop_tail_internal());
   }
 
-                inline void push_tail(Item* new_item) {
+  inline void push_tail(Item *new_item) {
     push_tail_internal(new_item);
   }
-            };
-        }
-    }
+};
+
+}
+}
 }
 
 #endif //PLS_DEQUE_H

lib/pls/include/pls/internal/data_structures/work_stealing_deque.h

+
+#ifndef PLS_WORK_STEALING_DEQUE_H_
+#define PLS_WORK_STEALING_DEQUE_H_
+
+#include <atomic>
+#include <mutex>
+#include <pls/internal/scheduling/thread_state.h>
+
+#include "pls/internal/base/system_details.h"
+#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/error_handling.h"
+
+#include "aligned_stack.h"
+
+namespace pls {
+namespace internal {
+namespace data_structures {
+
+using cas_integer = base::system_details::cas_integer;
+using pointer_t = base::system_details::pointer_t;
+static cas_integer get_stamp(cas_integer n) {
+  return (n & base::system_details::FIRST_HALF_CAS_INTEGER) >> ((sizeof(cas_integer) / 2) * 8);
+}
+static cas_integer get_offset(cas_integer n) {
+  return n & base::system_details::SECOND_HALF_CAS_INTEGER;
+}
+static cas_integer set_stamp(cas_integer n, cas_integer new_value) {
+  return (new_value << ((sizeof(cas_integer) / 2) * 8)) | (n & base::system_details::SECOND_HALF_CAS_INTEGER);
+}
+//static cas_integer set_offset(cas_integer n, cas_integer new_value) {
+//  return new_value | (n & base::system_details::FIRST_HALF_CAS_INTEGER);
+//}
+
+class work_stealing_deque_item {
+  // Pointer to the actual data
+  pointer_t data_;
+  // Index (relative to stack base) to the next and previous element
+  cas_integer next_item_;
+  cas_integer previous_item_;
+
+ public:
+  work_stealing_deque_item() : data_{0}, next_item_{0}, previous_item_{0} {}
+
+  template<typename Item>
+  Item *data() {
+    return reinterpret_cast<Item *>(data_);
+  }
+
+  template<typename Item>
+  void set_data(Item *data) {
+    data_ = reinterpret_cast<pointer_t >(data);
+  }
+
+  cas_integer next_item() {
+    return next_item_;
+  }
+  void set_next_item(cas_integer next_item) {
+    next_item_ = next_item;
+  }
+  cas_integer previous_item() {
+    return previous_item_;
+  }
+  void set_previous_item(cas_integer previous_item) {
+    previous_item_ = previous_item;
+  }
+};
+static_assert(sizeof(work_stealing_deque_item) < base::system_details::CACHE_LINE_SIZE,
+              "Work stealing deque relies on memory layout and requires cache lines to be longer than one 'work_stealing_deque_item' instance!");
+
+template<typename Item>
+class work_stealing_deque {
+  // Deque 'takes over' stack and handles memory management while in use.
+  // At any point in time the deque can stop using more memory and the stack can be used by other entities.
+  aligned_stack *stack_;
+  pointer_t base_pointer_;
+
+  std::atomic<cas_integer> head_;
+  std::atomic<cas_integer> tail_;
+  cas_integer previous_tail_;
+
+  base::spin_lock lock_{}; // TODO: Remove after debugging
+
+
+ public:
+  using state = aligned_stack::state;
+
+  explicit work_stealing_deque(aligned_stack *stack) : stack_{stack},
+                                                       base_pointer_{0},
+                                                       head_{0},
+                                                       tail_{0},
+                                                       previous_tail_{0} {
+    reset_base_pointer();
+  }
+  work_stealing_deque(const work_stealing_deque &other) : stack_{other.stack_},
+                                                          base_pointer_{other.base_pointer_},
+                                                          head_{other.head_.load()},
+                                                          tail_{other.tail_.load()},
+                                                          previous_tail_{other.previous_tail_} {}
+
+  void reset_base_pointer() {
+    base_pointer_ = reinterpret_cast<pointer_t >(stack_->save_state()); // Keep the base of our region in the stack
+  }
+
+  work_stealing_deque_item *item_at(cas_integer position) {
+    return reinterpret_cast<work_stealing_deque_item *>(base_pointer_
+        + (base::system_details::CACHE_LINE_SIZE * position));
+  }
+
+  cas_integer current_stack_offset() {
+    return (stack_->save_state() - base_pointer_) / base::system_details::CACHE_LINE_SIZE;
+  }
+
+  template<typename T>
+  std::pair<work_stealing_deque_item, T> *allocate_item(const T &new_item) {
+    // 'Union' type to push both on stack
+    using pair_t = std::pair<work_stealing_deque_item, T>;
+    // Allocate space on stack
+    auto new_pair = reinterpret_cast<pair_t *>(stack_->push<pair_t>());
+    // Initialize memory on stack
+    new((void *) &(new_pair->first)) work_stealing_deque_item();
+    new((void *) &(new_pair->second)) T(new_item);
+
+    return new_pair;
+  }
+
+  template<typename T>
+  Item *push_tail(const T &new_item) {
+    cas_integer local_tail = tail_;
+
+    auto new_pair = allocate_item(new_item);
+    // Prepare current tail to point to correct next items
+    auto tail_deque_item = item_at(local_tail);
+    tail_deque_item->set_data(&(new_pair->second));
+    tail_deque_item->set_next_item(current_stack_offset());
+    tail_deque_item->set_previous_item(previous_tail_);
+    previous_tail_ = local_tail;
+
+    // Linearization point, item appears after this write
+    cas_integer new_tail = current_stack_offset();
+    tail_ = new_tail;
+
+    return &(new_pair->second);
+  }
+
+  Item *pop_tail() {
+    cas_integer local_tail = tail_;
+    cas_integer local_head = head_;
+
+    if (local_tail <= get_offset(local_head)) {
+      return nullptr; // EMPTY
+    }
+
+    work_stealing_deque_item *previous_tail_item = item_at(previous_tail_);
+    cas_integer new_tail = previous_tail_;
+    previous_tail_ = previous_tail_item->previous_item();
+
+    // Publish our wish to set the tail back
+    tail_ = new_tail;
+    // Get the state of local head AFTER we published our wish
+    local_head = head_; // Linearization point, outside knows list is empty
+
+    if (get_offset(local_head) < new_tail) {
+      return previous_tail_item->data<Item>(); // Success, enough distance to other threads
+    }
+
+    if (get_offset(local_head) == new_tail) {
+      cas_integer new_head = set_stamp(new_tail, get_stamp(local_head) + 1);
+      // Try competing with consumers by updating the head's stamp value
+      if (head_.compare_exchange_strong(local_head, new_head)) {
+        return previous_tail_item->data<Item>(); // SUCCESS, we won the competition with other threads
+      }
+    }
+
+    // Some other thread either won the competition or it already set the head further than we are
+    // before we even tried to compete with it.
+    // Reset the queue into an empty state => head_ = tail_
+    tail_ = get_offset(local_head); // ...we give up to the other winning thread
+
+    return nullptr; // EMPTY, we lost the competition with other threads
+  }
+
+  Item *pop_head() {
+    cas_integer local_head = head_;
+    cas_integer local_tail = tail_;
+
+    if (local_tail <= get_offset(local_head)) {
+      return nullptr; // EMPTY
+    }
+    // Load info on current deque item.
+    // In case we have a race with a new (aba) overwritten item at this position,
+    // there has to be a competition over the tail -> the stamp increased and our next
+    // operation will fail anyways!
+    work_stealing_deque_item *head_deque_item = item_at(get_offset(local_head));
+    cas_integer next_item_offset = head_deque_item->next_item();
+    Item *head_data_item = head_deque_item->data<Item>();
+
+    // We try to set the head to this new position.
+    // Possible outcomes:
+    // 1) no one interrupted us, we win this competition
+    // 2) other thread took the head, we lose to this
+    // 3) owning thread removed tail, we lose to this
+    cas_integer new_head = set_stamp(next_item_offset, get_stamp(local_head) + 1);
+    if (head_.compare_exchange_strong(local_head, new_head)) {
+      return head_data_item; // SUCCESS, we won the competition
+    }
+
+    return nullptr; // EMPTY, we lost the competition
+
+  }
+
+  void release_memory_until(state state) {
+    cas_integer item_offset = (state - base_pointer_) / base::system_details::CACHE_LINE_SIZE;
+
+    cas_integer local_head = head_;
+    cas_integer local_tail = tail_;
+
+    stack_->reset_state(state);
+
+    if (item_offset < local_tail) {
+      tail_ = item_offset;
+      if (get_offset(local_head) >= local_tail) {
+        head_ = set_stamp(item_offset, get_stamp(local_head) + 1);
+      }
+    }
+  }
+
+  void release_memory_until(Item *item) {
+    release_memory_until(reinterpret_cast<pointer_t >(item));
+  }
+
+  state save_state() {
+    return stack_->save_state();
+  }
+};
+
+}
+}
+}
+
+#endif //PLS_WORK_STEALING_DEQUE_H_

lib/pls/include/pls/internal/helpers/mini_benchmark.h

@@ -9,11 +9,12 @@
 #include <iostream>
 
 namespace pls {
-    namespace internal {
-        namespace helpers {
-            // TODO: Clean up (separate into small functions and .cpp file)
-            template<typename Function>
-            void run_mini_benchmark(const Function& lambda, size_t max_threads, unsigned long max_runtime_ms=1000) {
+namespace internal {
+namespace helpers {
+
+// TODO: Clean up (separate into small functions and .cpp file)
+template<typename Function>
+void run_mini_benchmark(const Function &lambda, size_t max_threads, unsigned long max_runtime_ms = 1000) {
   using namespace std;
   using namespace pls::internal::scheduling;
 
@@ -37,7 +38,7 @@ namespace pls {
     });
 
     long time = chrono::duration_cast<chrono::microseconds>(end_time - start_time).count();
-                    double time_per_iteration = (double)time / iterations;
+    double time_per_iteration = (double) time / iterations;
 
     std::cout << time_per_iteration;
     if (num_threads < max_threads) {
@@ -45,9 +46,10 @@ namespace pls {
     }
   }
   std::cout << std::endl;
-            }
-        }
-    }
+}
+
+}
+}
 }
 
 #endif //PLS_MINI_BENCHMARK_H

lib/pls/include/pls/internal/helpers/prohibit_new.h

@@ -15,7 +15,7 @@
 #ifdef NEW_LINK_ERROR
 // This will cause a linker error if new is used in the code.
 // We also exit if it is somehow still called.
-inline void * operator new (std::size_t) {
+inline void *operator new(std::size_t) {
   extern int bare_new_erroneously_called();
   exit(bare_new_erroneously_called() | 1);
 }

lib/pls/include/pls/internal/helpers/unique_id.h

@@ -7,12 +7,13 @@
 #include <stdint.h>
 
 namespace pls {
-    namespace internal {
-        namespace helpers {
-            struct unique_id {
+namespace internal {
+namespace helpers {
+
+struct unique_id {
   const uint32_t id_;
-                const std::type_info& type_;
-                bool operator==(const unique_id& other) const { return id_ == other.id_ && type_ == other.type_; }
+  const std::type_info &type_;
+  bool operator==(const unique_id &other) const { return id_ == other.id_ && type_ == other.type_; }
 
   static constexpr unique_id create(const uint32_t id) {
     return unique_id(id, typeid(void));
@@ -22,10 +23,11 @@ namespace pls {
     return unique_id(UINT32_MAX, typeid(std::tuple<T...>));
   }
  private:
-                explicit constexpr unique_id(const uint32_t id, const std::type_info& type): id_{id}, type_{type} {};
-            };
-        }
-    }
+  explicit constexpr unique_id(const uint32_t id, const std::type_info &type) : id_{id}, type_{type} {};
+};
+
+}
+}
 }
 
 #endif //PLS_UNIQUE_ID_H

lib/pls/include/pls/internal/scheduling/abstract_task.h

@@ -2,42 +2,44 @@
 #ifndef PLS_ABSTRACT_TASK_H
 #define PLS_ABSTRACT_TASK_H
 
-#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 #include "pls/internal/helpers/unique_id.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            class abstract_task {
+namespace internal {
+namespace scheduling {
+
+class abstract_task {
  public:
   using id = helpers::unique_id;
 
  private:
   unsigned int depth_;
   abstract_task::id unique_id_;
-                abstract_task* child_task_;
+  abstract_task *volatile child_task_;
 
  public:
-                abstract_task(const unsigned int depth, const abstract_task::id& unique_id):
+  abstract_task(const unsigned int depth, const abstract_task::id &unique_id) :
       depth_{depth},
       unique_id_{unique_id},
       child_task_{nullptr} {}
 
   virtual void execute() = 0;
-                void set_child(abstract_task* child_task) { child_task_ = child_task; }
-                abstract_task* child() { return child_task_; }
+  void set_child(abstract_task *child_task) { child_task_ = child_task; }
+  abstract_task *child() const { return child_task_; }
 
   void set_depth(unsigned int depth) { depth_ = depth; }
   unsigned int depth() const { return depth_; }
   id unique_id() const { return unique_id_; }
  protected:
-                virtual bool internal_stealing(abstract_task* other_task) = 0;
-                virtual bool split_task(base::spin_lock* lock) = 0;
+  virtual bool internal_stealing(abstract_task *other_task) = 0;
+  virtual bool split_task(base::swmr_spin_lock *lock) = 0;
 
   bool steal_work();
-            };
-        }
-    }
+};
+
+}
+}
 }
 
 #endif //PLS_ABSTRACT_TASK_H

lib/pls/include/pls/internal/scheduling/fork_join_task.h

@@ -5,30 +5,34 @@
 #include "pls/internal/helpers/profiler.h"
 
 #include "pls/internal/data_structures/aligned_stack.h"
-#include "pls/internal/data_structures/deque.h"
+#include "pls/internal/data_structures/work_stealing_deque.h"
 
 #include "abstract_task.h"
 #include "thread_state.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            class fork_join_task;
-            class fork_join_sub_task: public data_structures::deque_item {
+namespace internal {
+namespace scheduling {
+
+class fork_join_task;
+class fork_join_sub_task {
   friend class fork_join_task;
 
   // Coordinate finishing of sub_tasks
   std::atomic_uint32_t ref_count_;
-                fork_join_sub_task* parent_;
+  fork_join_sub_task *parent_;
 
   // Access to TBB scheduling environment
-                fork_join_task* tbb_task_;
+  fork_join_task *tbb_task_;
+
+  bool executed = false;
+  int executed_at = -1;
 
   // Stack Management (reset stack pointer after wait_for_all() calls)
-                data_structures::aligned_stack::state stack_state_;
+  data_structures::work_stealing_deque<fork_join_sub_task>::state deque_state_;
  protected:
   explicit fork_join_sub_task();
-                fork_join_sub_task(const fork_join_sub_task& other);
+  fork_join_sub_task(const fork_join_sub_task &other);
 
   // Overwritten with behaviour of child tasks
   virtual void execute_internal() = 0;
@@ -36,63 +40,84 @@ namespace pls {
  public:
   // Only use them when actually executing this sub_task (only public for simpler API design)
   template<typename T>
-                void spawn_child(const T& sub_task);
+  void spawn_child(T &sub_task);
   void wait_for_all();
 
+  static fork_join_sub_task *current();
  private:
-                void spawn_child_internal(fork_join_sub_task* sub_task);
   void execute();
-            };
+};
+
+template<typename Function>
+class fork_join_lambda_by_reference : public fork_join_sub_task {
+  const Function &function_;
+
+ public:
+  explicit fork_join_lambda_by_reference(const Function &function) : fork_join_sub_task{}, function_{function} {};
 
-            template<typename Function>
-            class fork_join_lambda: public fork_join_sub_task {
-                const Function* function_;
+ protected:
+  void execute_internal() override {
+    function_();
+  }
+};
+
+template<typename Function>
+class fork_join_lambda_by_value : public fork_join_sub_task {
+  const Function function_;
 
  public:
-                explicit fork_join_lambda(const Function* function): function_{function} {};
+  explicit fork_join_lambda_by_value(const Function &function) : fork_join_sub_task{}, function_{function} {};
 
  protected:
   void execute_internal() override {
-                    (*function_)(this);
+    function_();
   }
-            };
+};
 
-            class fork_join_task: public abstract_task {
+class fork_join_task : public abstract_task {
   friend class fork_join_sub_task;
 
-                fork_join_sub_task* root_task_;
-                fork_join_sub_task* currently_executing_;
-                data_structures::aligned_stack* my_stack_;
+  fork_join_sub_task *root_task_;
+  fork_join_sub_task *currently_executing_;
 
   // Double-Ended Queue management
-                data_structures::deque<fork_join_sub_task> deque_;
+  data_structures::work_stealing_deque<fork_join_sub_task> deque_;
 
   // Steal Management
-                fork_join_sub_task* last_stolen_;
+  fork_join_sub_task *last_stolen_;
 
-                fork_join_sub_task* get_local_sub_task();
-                fork_join_sub_task* get_stolen_sub_task();
+  fork_join_sub_task *get_local_sub_task();
+  fork_join_sub_task *get_stolen_sub_task();
 
-            protected:
-                bool internal_stealing(abstract_task* other_task) override;
-                bool split_task(base::spin_lock* /*lock*/) override;
+  bool internal_stealing(abstract_task *other_task) override;
+  bool split_task(base::swmr_spin_lock * /*lock*/) override;
 
  public:
-                explicit fork_join_task(fork_join_sub_task* root_task, const abstract_task::id& id);
+  explicit fork_join_task(fork_join_sub_task *root_task, const abstract_task::id &id);
   void execute() override;
-                fork_join_sub_task* currently_executing() const;
-            };
+  fork_join_sub_task *currently_executing() const;
+};
 
-            template<typename T>
-            void fork_join_sub_task::spawn_child(const T& task) {
+template<typename T>
+void fork_join_sub_task::spawn_child(T &task) {
   PROFILE_FORK_JOIN_STEALING("spawn_child")
   static_assert(std::is_base_of<fork_join_sub_task, T>::value, "Only pass fork_join_sub_task subclasses!");
 
-                T* new_task = tbb_task_->my_stack_->push(task);
-                spawn_child_internal(new_task);
-            }
-        }
-    }
+  // Keep our refcount up to date
+  ref_count_++;
+
+  // Assign forced values
+  task.parent_ = this;
+  task.tbb_task_ = tbb_task_;
+  task.deque_state_ = tbb_task_->deque_.save_state();
+
+  // Push on our deque
+  const T const_task = task;
+  tbb_task_->deque_.push_tail(const_task);
+}
+
+}
+}
 }
 
 #endif //PLS_TBB_LIKE_TASK_H

lib/pls/include/pls/internal/scheduling/root_task.h

@@ -5,25 +5,26 @@
 #include <mutex>
 
 #include "pls/internal/helpers/profiler.h"
-#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 
 #include "abstract_task.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            class root_task : public abstract_task {
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+class root_task : public abstract_task {
   Function function_;
   std::atomic_uint8_t finished_;
  public:
   static constexpr auto create_id = helpers::unique_id::create<root_task<Function>>;
 
-                explicit root_task(Function function):
+  explicit root_task(Function function) :
       abstract_task{0, create_id()},
       function_{function},
       finished_{0} {}
-                root_task(const root_task& other):
+  root_task(const root_task &other) :
       abstract_task{0, create_id()},
       function_{other.function_},
       finished_{0} {}
@@ -38,23 +39,23 @@ namespace pls {
     finished_ = 1;
   }
 
-                bool internal_stealing(abstract_task* /*other_task*/) override {
+  bool internal_stealing(abstract_task * /*other_task*/) override {
     return false;
   }
 
-                bool split_task(base::spin_lock* /*lock*/) override {
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
     return false;
   }
-            };
+};
 
-            template<typename Function>
-            class root_worker_task : public abstract_task {
-                root_task<Function>* master_task_;
+template<typename Function>
+class root_worker_task : public abstract_task {
+  root_task<Function> *master_task_;
 
  public:
   static constexpr auto create_id = root_task<Function>::create_id;
 
-                explicit root_worker_task(root_task<Function>* master_task):
+  explicit root_worker_task(root_task<Function> *master_task) :
       abstract_task{0, create_id()},
       master_task_{master_task} {}
 
@@ -65,16 +66,17 @@ namespace pls {
     } while (!master_task_->finished());
   }
 
-                bool internal_stealing(abstract_task* /*other_task*/) override {
+  bool internal_stealing(abstract_task * /*other_task*/) override {
     return false;
   }
 
-                bool split_task(base::spin_lock* /*lock*/) override {
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
     return false;
   }
-            };
-        }
-    }
+};
+
+}
+}
 }
 
 #endif //PLS_ROOT_MASTER_TASK_H

lib/pls/include/pls/internal/scheduling/run_on_n_threads_task.h

@@ -12,12 +12,14 @@
 #include "scheduler.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            class run_on_n_threads_task : public abstract_task {
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+class run_on_n_threads_task : public abstract_task {
   template<typename F>
-                friend class run_on_n_threads_task_worker;
+  friend
+  class run_on_n_threads_task_worker;
 
   Function function_;
 
@@ -38,7 +40,7 @@ namespace pls {
  public:
   static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task<Function>>;
 
-                run_on_n_threads_task(Function function, int num_threads):
+  run_on_n_threads_task(Function function, int num_threads) :
       abstract_task{0, create_id()},
       function_{function},
       counter{num_threads - 1} {}
@@ -55,21 +57,21 @@ namespace pls {
     std::cout << "Finished Master!" << std::endl;
   }
 
-                bool internal_stealing(abstract_task* /*other_task*/) override {
+  bool internal_stealing(abstract_task * /*other_task*/) override {
     return false;
   }
 
-                bool split_task(base::spin_lock* lock) override;
-            };
+  bool split_task(base::swmr_spin_lock *lock) override;
+};
 
-            template<typename Function>
-            class run_on_n_threads_task_worker : public abstract_task {
+template<typename Function>
+class run_on_n_threads_task_worker : public abstract_task {
   Function function_;
-                run_on_n_threads_task<Function>* root_;
+  run_on_n_threads_task<Function> *root_;
  public:
   static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task_worker<Function>>;
 
-                run_on_n_threads_task_worker(Function function, run_on_n_threads_task<Function>* root):
+  run_on_n_threads_task_worker(Function function, run_on_n_threads_task<Function> *root) :
       abstract_task{0, create_id()},
       function_{function},
       root_{root} {}
@@ -83,36 +85,36 @@ namespace pls {
     }
   }
 
-                bool internal_stealing(abstract_task* /*other_task*/) override {
+  bool internal_stealing(abstract_task * /*other_task*/) override {
     return false;
   }
 
-                bool split_task(base::spin_lock* /*lock*/) override {
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
     return false;
   }
-            };
+};
 
-            template<typename Function>
-            bool run_on_n_threads_task<Function>::split_task(base::spin_lock* lock) {
+template<typename Function>
+bool run_on_n_threads_task<Function>::split_task(base::swmr_spin_lock *lock) {
   if (get_counter() <= 0) {
     return false;
   }
   // In success case, unlock.
-                // TODO: this locking is complicated and error prone.
-                lock->unlock();
+  lock->reader_unlock();
 
   auto scheduler = base::this_thread::state<thread_state>()->scheduler_;
   auto task = run_on_n_threads_task_worker<Function>{function_, this};
   scheduler->execute_task(task, depth());
   return true;
-            }
+}
 
-            template<typename Function>
-            run_on_n_threads_task<Function> create_run_on_n_threads_task(Function function, int num_threads) {
+template<typename Function>
+run_on_n_threads_task<Function> create_run_on_n_threads_task(Function function, int num_threads) {
   return run_on_n_threads_task<Function>{function, num_threads};
-            }
-        }
-    }
+}
+
+}
+}
 }
 
 #endif //PLS_RUN_ON_N_THREADS_TASK_H

lib/pls/include/pls/internal/scheduling/scheduler.h

@@ -17,21 +17,22 @@
 #include "scheduler_memory.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            void worker_routine();
-            using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+namespace internal {
+namespace scheduling {
 
-            class scheduler {
+void worker_routine();
+using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+
+class scheduler {
   friend void worker_routine();
 
   const unsigned int num_threads_;
-                scheduler_memory* memory_;
+  scheduler_memory *memory_;
 
   base::barrier sync_barrier_;
   bool terminated_;
  public:
-                explicit scheduler(scheduler_memory* memory, unsigned int num_threads);
+  explicit scheduler(scheduler_memory *memory, unsigned int num_threads);
   ~scheduler();
 
   /**
@@ -50,17 +51,18 @@ namespace pls {
    * @param depth Optional: depth of the new task, otherwise set implicitly.
    */
   template<typename Task>
-                static void execute_task(Task& task, int depth=-1);
+  static void execute_task(Task &task, int depth = -1);
 
-                static abstract_task* current_task() { return base::this_thread::state<thread_state>()->current_task_; }
+  static abstract_task *current_task() { return base::this_thread::state<thread_state>()->current_task_; }
 
-                void terminate(bool wait_for_workers=true);
+  void terminate(bool wait_for_workers = true);
 
   unsigned int num_threads() const { return num_threads_; }
-                thread_state* thread_state_for(size_t id) { return memory_->thread_state_for(id); }
-            };
-        }
-    }
+  thread_state *thread_state_for(size_t id) { return memory_->thread_state_for(id); }
+};
+
+}
+}
 }
 #include "scheduler_impl.h"
 

lib/pls/include/pls/internal/scheduling/scheduler_impl.h

@@ -3,10 +3,11 @@
 #define PLS_SCHEDULER_IMPL_H
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            void scheduler::perform_work(Function work_section) {
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+void scheduler::perform_work(Function work_section) {
   PROFILE_WORK_BLOCK("scheduler::perform_work")
   root_task<Function> master{work_section};
 
@@ -31,42 +32,45 @@ namespace pls {
     root_worker_task<Function> worker{new_master};
     memory_->task_stack_for(0)->pop<typeof(worker)>();
   }
-            }
+}
 
-            template<typename Task>
-            void scheduler::execute_task(Task& task, int depth) {
+template<typename Task>
+void scheduler::execute_task(Task &task, int depth) {
   static_assert(std::is_base_of<abstract_task, Task>::value, "Only pass abstract_task subclasses!");
 
   auto my_state = base::this_thread::state<thread_state>();
-                abstract_task* old_task;
-                abstract_task* new_task;
+  abstract_task *old_task;
+  abstract_task *new_task;
 
   // Init Task
-                {
-                    std::lock_guard<base::spin_lock> lock{my_state->lock_};
   old_task = my_state->current_task_;
   new_task = my_state->task_stack_->push(task);
 
   new_task->set_depth(depth >= 0 ? depth : old_task->depth() + 1);
+
+  {
+    my_state->lock_.writer_lock();
     my_state->current_task_ = new_task;
     old_task->set_child(new_task);
+    my_state->lock_.writer_unlock();
   }
 
   // Run Task
   new_task->execute();
 
   // Teardown state back to before the task was executed
-                {
-                    std::lock_guard<base::spin_lock> lock{my_state->lock_};
+  my_state->task_stack_->pop<Task>();
 
+  {
+    my_state->lock_.writer_lock();
     old_task->set_child(nullptr);
     my_state->current_task_ = old_task;
-
-                    my_state->task_stack_->pop<Task>();
-                }
-            }
-        }
+    my_state->lock_.writer_unlock();
   }
 }
 
+}
+}
+}
+
 #endif //PLS_SCHEDULER_IMPL_H

lib/pls/include/pls/internal/scheduling/scheduler_memory.h

@@ -7,21 +7,22 @@
 #define PLS_SCHEDULER_MEMORY_H
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            void worker_routine();
-            using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+namespace internal {
+namespace scheduling {
 
-            class scheduler_memory {
+void worker_routine();
+using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+
+class scheduler_memory {
  public:
   virtual size_t max_threads() const = 0;
-                virtual thread_state* thread_state_for(size_t id) = 0;
-                virtual scheduler_thread* thread_for(size_t id) = 0;
-                virtual data_structures::aligned_stack* task_stack_for(size_t id) = 0;
-            };
+  virtual thread_state *thread_state_for(size_t id) = 0;
+  virtual scheduler_thread *thread_for(size_t id) = 0;
+  virtual data_structures::aligned_stack *task_stack_for(size_t id) = 0;
+};
 
-            template<size_t MAX_THREADS, size_t TASK_STACK_SIZE>
-            class static_scheduler_memory: public scheduler_memory {
+template<size_t MAX_THREADS, size_t TASK_STACK_SIZE>
+class static_scheduler_memory : public scheduler_memory {
   // Everyone of these types has to live on its own cache line,
   // as each thread uses one of them independently.
   // Therefore it would be a major performance hit if we shared cache lines on these.
@@ -38,17 +39,18 @@ namespace pls {
  public:
   static_scheduler_memory() {
     for (size_t i = 0; i < MAX_THREADS; i++) {
-                        new ((void*)task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i].pointer()->data(), TASK_STACK_SIZE);
+      new((void *) task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i].pointer()->data(),
+                                                                             TASK_STACK_SIZE);
     }
   }
 
   size_t max_threads() const override { return MAX_THREADS; }
-                thread_state* thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
-                scheduler_thread* thread_for(size_t id) override { return threads_[id].pointer(); }
-                data_structures::aligned_stack* task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
-            };
+  thread_state *thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
+  scheduler_thread *thread_for(size_t id) override { return threads_[id].pointer(); }
+  data_structures::aligned_stack *task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
+};
 
-            class malloc_scheduler_memory: public scheduler_memory {
+class malloc_scheduler_memory : public scheduler_memory {
   // Everyone of these types has to live on its own cache line,
   // as each thread uses one of them independently.
   // Therefore it would be a major performance hit if we shared cache lines on these.
@@ -58,21 +60,22 @@ namespace pls {
 
   const size_t num_threads_;
 
-                aligned_thread* threads_;
-                aligned_thread_state * thread_states_;
-                char** task_stacks_memory_;
-                aligned_aligned_stack * task_stacks_;
+  aligned_thread *threads_;
+  aligned_thread_state *thread_states_;
+  char **task_stacks_memory_;
+  aligned_aligned_stack *task_stacks_;
  public:
   explicit malloc_scheduler_memory(size_t num_threads, size_t memory_per_stack = 2 << 16);
   ~malloc_scheduler_memory();
 
   size_t max_threads() const override { return num_threads_; }
-                thread_state* thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
-                scheduler_thread* thread_for(size_t id) override { return threads_[id].pointer(); }
-                data_structures::aligned_stack* task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
-            };
-        }
-    }
+  thread_state *thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
+  scheduler_thread *thread_for(size_t id) override { return threads_[id].pointer(); }
+  data_structures::aligned_stack *task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
+};
+
+}
+}
 }
 
 #endif //PLS_SCHEDULER_MEMORY_H

lib/pls/include/pls/internal/scheduling/thread_state.h

@@ -5,41 +5,46 @@
 #include <random>
 
 #include "pls/internal/data_structures/aligned_stack.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 #include "abstract_task.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            // forward declaration
-            class scheduler;
-
-            struct thread_state {
-                scheduler* scheduler_;
-                abstract_task* root_task_;
-                abstract_task* current_task_;
-                data_structures::aligned_stack* task_stack_;
-                size_t id_;
-                base::spin_lock lock_;
-                std::minstd_rand random_;
-
-                thread_state():
+namespace internal {
+namespace scheduling {
+
+// forward declaration
+class scheduler;
+
+struct thread_state {
+  alignas(base::system_details::CACHE_LINE_SIZE) scheduler *scheduler_;
+  alignas(base::system_details::CACHE_LINE_SIZE) abstract_task *root_task_;
+  alignas(base::system_details::CACHE_LINE_SIZE) abstract_task *current_task_;
+  alignas(base::system_details::CACHE_LINE_SIZE) data_structures::aligned_stack *task_stack_;
+  alignas(base::system_details::CACHE_LINE_SIZE) size_t id_;
+  alignas(base::system_details::CACHE_LINE_SIZE) base::swmr_spin_lock lock_;
+  alignas(base::system_details::CACHE_LINE_SIZE) std::minstd_rand random_;
+
+  thread_state() :
       scheduler_{nullptr},
       root_task_{nullptr},
       current_task_{nullptr},
       task_stack_{nullptr},
       id_{0},
+      lock_{},
       random_{id_} {};
 
-                thread_state(scheduler* scheduler, data_structures::aligned_stack* task_stack, unsigned int id):
+  thread_state(scheduler *scheduler, data_structures::aligned_stack *task_stack, unsigned int id) :
       scheduler_{scheduler},
       root_task_{nullptr},
       current_task_{nullptr},
       task_stack_{task_stack},
       id_{id},
+      lock_{},
       random_{id_} {}
-            };
-        }
-    }
+};
+
+}
+}
 }
 
 #endif //PLS_THREAD_STATE_H

lib/pls/include/pls/pls.h

@@ -8,18 +8,22 @@
 #include "pls/internal/helpers/unique_id.h"
 
 namespace pls {
-    using internal::scheduling::static_scheduler_memory;
-    using internal::scheduling::malloc_scheduler_memory;
 
-    using internal::scheduling::scheduler;
-    using task_id = internal::scheduling::abstract_task::id;
+using internal::scheduling::static_scheduler_memory;
+using internal::scheduling::malloc_scheduler_memory;
 
-    using unique_id = internal::helpers::unique_id;
+using internal::scheduling::scheduler;
+using task_id = internal::scheduling::abstract_task::id;
 
-    using internal::scheduling::fork_join_sub_task;
-    using internal::scheduling::fork_join_task;
+using unique_id = internal::helpers::unique_id;
+
+using internal::scheduling::fork_join_sub_task;
+using internal::scheduling::fork_join_lambda_by_reference;
+using internal::scheduling::fork_join_lambda_by_value;
+using internal::scheduling::fork_join_task;
+
+using algorithm::invoke_parallel;
 
-    using algorithm::invoke_parallel;
 }
 
 #endif

lib/pls/src/internal/base/alignment.cpp

@@ -2,26 +2,37 @@
 #include "pls/internal/base/system_details.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            namespace alignment {
-                void* allocate_aligned(size_t size) {
+namespace internal {
+namespace base {
+namespace alignment {
+
+void *allocate_aligned(size_t size) {
   return aligned_alloc(system_details::CACHE_LINE_SIZE, size);
-                }
+}
 
-                std::uintptr_t next_alignment(std::uintptr_t size) {
-                    std::uintptr_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
+system_details::pointer_t next_alignment(system_details::pointer_t size) {
+  system_details::pointer_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
   if (miss_alignment == 0) {
     return size;
   } else {
     return size + (base::system_details::CACHE_LINE_SIZE - miss_alignment);
   }
-                }
+}
 
-                char* next_alignment(char* pointer) {
-                    return reinterpret_cast<char*>(next_alignment(reinterpret_cast<std::uintptr_t >(pointer)));
-                }
-            }
-        }
+system_details::pointer_t previous_alignment(system_details::pointer_t size) {
+  system_details::pointer_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
+  if (miss_alignment == 0) {
+    return size;
+  } else {
+    return size - miss_alignment;
   }
 }
+
+char *next_alignment(char *pointer) {
+  return reinterpret_cast<char *>(next_alignment(reinterpret_cast<system_details::pointer_t >(pointer)));
+}
+
+}
+}
+}
+}

lib/pls/src/internal/base/barrier.cpp

 #include "pls/internal/base/barrier.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            barrier::barrier(const unsigned int count): barrier_{} {
+namespace internal {
+namespace base {
+
+barrier::barrier(const unsigned int count) : barrier_{} {
   pthread_barrier_init(&barrier_, nullptr, count);
-            }
+}
 
-            barrier::~barrier() {
+barrier::~barrier() {
   pthread_barrier_destroy(&barrier_);
-            }
+}
 
-            void barrier::wait() {
+void barrier::wait() {
   pthread_barrier_wait(&barrier_);
-            }
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/base/swmr_spin_lock.cpp

+#include "pls/internal/base/swmr_spin_lock.h"
+#include "pls/internal/base/system_details.h"
+
+namespace pls {
+namespace internal {
+namespace base {
+
+bool swmr_spin_lock::reader_try_lock() {
+  PROFILE_LOCK("Try Acquire Read Lock")
+  if (write_request_.load(std::memory_order_acquire) == 1) {
+    return false;
+  }
+  // We think we can enter the region
+  readers_.fetch_add(1, std::memory_order_acquire);
+  if (write_request_.load(std::memory_order_acquire) == 1) {
+    // Whoops, the writer acquires the lock, so we back off again
+    readers_.fetch_add(-1, std::memory_order_release);
+    return false;
+  }
+
+  return true;
+}
+
+void swmr_spin_lock::reader_unlock() {
+  PROFILE_LOCK("Release Read Lock")
+  readers_--;
+}
+
+void swmr_spin_lock::writer_lock() {
+  PROFILE_LOCK("Acquire Write Lock")
+  // Tell the readers that we would like to write
+  write_request_ = 1;
+
+  // Wait for all of them to exit the critical section
+  while (readers_ > 0)
+    system_details::relax_cpu(); // Spin, not expensive as relaxed load
+}
+
+void swmr_spin_lock::writer_unlock() {
+  PROFILE_LOCK("Release Write Lock")
+  write_request_ = 0;
+}
+
+}
+}
+}

lib/pls/src/internal/base/tas_spin_lock.cpp

 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/base/tas_spin_lock.h"
+#include "pls/internal/base/backoff.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            void tas_spin_lock::lock() {
+namespace internal {
+namespace base {
+
+void tas_spin_lock::lock() {
   PROFILE_LOCK("Acquire Lock")
-                int tries = 0;
-                while (flag_.test_and_set(std::memory_order_acquire)) {
-                    tries++;
-                    if (tries % yield_at_tries_ == 0) {
-                        this_thread::yield();
-                    }
+  backoff backoff_strategy;
+
+  while (true) {
+    if (flag_.test_and_set(std::memory_order_acquire) == 0) {
+      return;
     }
+    backoff_strategy.do_backoff();
   }
+}
 
-            bool tas_spin_lock::try_lock(unsigned int num_tries) {
+bool tas_spin_lock::try_lock(unsigned int num_tries) {
   PROFILE_LOCK("Try Acquire Lock")
-                while (flag_.test_and_set(std::memory_order_acquire)) {
+  backoff backoff_strategy;
+
+  while (true) {
+    if (flag_.test_and_set(std::memory_order_acquire) == 0) {
+      return true;
+    }
+
     num_tries--;
     if (num_tries <= 0) {
       return false;
     }
+
+    backoff_strategy.do_backoff();
   }
-                return true;
-            }
+}
 
-            void tas_spin_lock::unlock() {
+void tas_spin_lock::unlock() {
+  PROFILE_LOCK("Unlock")
   flag_.clear(std::memory_order_release);
-            }
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/base/thread.cpp

 #include "pls/internal/base/thread.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
+namespace internal {
+namespace base {
+
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-            pthread_key_t this_thread::local_storage_key_ = false;
-            bool this_thread::local_storage_key_initialized_;
+pthread_key_t this_thread::local_storage_key_ = false;
+bool this_thread::local_storage_key_initialized_;
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-            __thread void* this_thread::local_state_;
+__thread void *this_thread::local_state_;
 #endif
-            // implementation in header (C++ templating)
-        }
-    }
+// implementation in header (C++ templating)
+
+}
+}
 }

lib/pls/src/internal/base/ttas_spin_lock.cpp

 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/base/ttas_spin_lock.h"
+#include "pls/internal/base/backoff.h"
 
 namespace pls {
-    namespace internal {
-        namespace base {
-            void ttas_spin_lock::lock() {
+namespace internal {
+namespace base {
+
+void ttas_spin_lock::lock() {
   PROFILE_LOCK("Acquire Lock")
-                int tries = 0;
   int expected = 0;
+  backoff backoff_;
 
-                do {
-                    while (flag_.load(std::memory_order_relaxed) == 1) {
-                        tries++;
-                        if (tries % yield_at_tries_ == 0) {
-                            this_thread::yield();
-                        }
-                    }
+  while (true) {
+    while (flag_.load(std::memory_order_relaxed) == 1)
+      system_details::relax_cpu(); // Spin
 
     expected = 0;
-                } while (!flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire));
+    if (flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire)) {
+      return;
     }
+    backoff_.do_backoff();
+  }
+}
 
-            bool ttas_spin_lock::try_lock(unsigned int num_tries) {
+bool ttas_spin_lock::try_lock(unsigned int num_tries) {
   PROFILE_LOCK("Try Acquire Lock")
   int expected = 0;
+  backoff backoff_;
 
-                do {
-                    while (flag_.load(std::memory_order_relaxed) == 1) {
+  while (true) {
+    while (flag_.load() == 1) {
       num_tries--;
       if (num_tries <= 0) {
         return false;
       }
+      system_details::relax_cpu();
     }
 
     expected = 0;
-                } while (!flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire));
-
+    if (flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire)) {
       return true;
     }
-
-            void ttas_spin_lock::unlock() {
-                flag_.store(0, std::memory_order_release);
-            }
+    num_tries--;
+    if (num_tries <= 0) {
+      return false;
     }
+    backoff_.do_backoff();
   }
 }
+
+void ttas_spin_lock::unlock() {
+  PROFILE_LOCK("Unlock")
+  flag_.store(0, std::memory_order_release);
+}
+
+}
+}
+}

lib/pls/src/internal/data_structures/aligned_stack.cpp

@@ -2,12 +2,19 @@
 #include "pls/internal/base/system_details.h"
 
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            aligned_stack::aligned_stack(char* memory_region, const std::size_t size):
+namespace internal {
+namespace data_structures {
+
+aligned_stack::aligned_stack(pointer_t memory_region, const std::size_t size) :
     memory_start_{memory_region},
     memory_end_{memory_region + size},
     head_{base::alignment::next_alignment(memory_start_)} {}
-        }
-    }
+
+aligned_stack::aligned_stack(char *memory_region, const std::size_t size) :
+    memory_start_{(pointer_t) memory_region},
+    memory_end_{(pointer_t) memory_region + size},
+    head_{base::alignment::next_alignment(memory_start_)} {}
+
+}
+}
 }

lib/pls/src/internal/data_structures/deque.cpp

@@ -3,56 +3,58 @@
 #include "pls/internal/data_structures/deque.h"
 
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            deque_item* deque_internal::pop_head_internal() {
+namespace internal {
+namespace data_structures {
+
+deque_item *deque_internal::pop_head_internal() {
   std::lock_guard<base::spin_lock> lock{lock_};
 
   if (head_ == nullptr) {
     return nullptr;
   }
 
-                deque_item* result = head_;
-                head_ = head_->prev_;
+  deque_item *result = head_;
+  head_ = head_->next_;
   if (head_ == nullptr) {
     tail_ = nullptr;
   } else {
-                    head_->next_ = nullptr;
+    head_->prev_ = nullptr;
   }
 
   return result;
-            }
+}
 
-            deque_item* deque_internal::pop_tail_internal() {
+deque_item *deque_internal::pop_tail_internal() {
   std::lock_guard<base::spin_lock> lock{lock_};
 
   if (tail_ == nullptr) {
     return nullptr;
   }
 
-                deque_item* result = tail_;
-                tail_ = tail_->next_;
+  deque_item *result = tail_;
+  tail_ = tail_->prev_;
   if (tail_ == nullptr) {
     head_ = nullptr;
   } else {
-                    tail_->prev_ = nullptr;
+    tail_->next_ = nullptr;
   }
 
   return result;
-            }
+}
 
-            void deque_internal::push_tail_internal(deque_item *new_item) {
+void deque_internal::push_tail_internal(deque_item *new_item) {
   std::lock_guard<base::spin_lock> lock{lock_};
 
   if (tail_ != nullptr) {
-                    tail_->prev_ = new_item;
+    tail_->next_ = new_item;
   } else {
     head_ = new_item;
   }
-                new_item->next_ = tail_;
-                new_item->prev_ = nullptr;
+  new_item->prev_ = tail_;
+  new_item->next_ = nullptr;
   tail_ = new_item;
-            }
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/scheduling/abstract_task.cpp

+#include <pls/internal/base/backoff.h>
 #include "pls/internal/helpers/profiler.h"
 
 #include "pls/internal/scheduling/thread_state.h"
@@ -5,31 +6,35 @@
 #include "pls/internal/scheduling/scheduler.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            bool abstract_task::steal_work() {
+namespace internal {
+namespace scheduling {
+
+bool abstract_task::steal_work() {
+  thread_local static base::backoff backoff{};
+
   PROFILE_STEALING("abstract_task::steal_work")
   const auto my_state = base::this_thread::state<thread_state>();
   const auto my_scheduler = my_state->scheduler_;
 
   const size_t my_id = my_state->id_;
   const size_t offset = my_state->random_() % my_scheduler->num_threads();
-                const size_t max_tries = 1; // my_scheduler->num_threads(); TODO: Tune this value
+  const size_t max_tries = my_scheduler->num_threads() - 1; // TODO: Tune this value
   for (size_t i = 0; i < max_tries; i++) {
     size_t target = (offset + i) % my_scheduler->num_threads();
     if (target == my_id) {
-                        continue;
+      target = (target + 1) % my_scheduler->num_threads();
     }
     auto target_state = my_scheduler->thread_state_for(target);
 
-                    // TODO: Cleaner Locking Using std::guarded_lock
-                    target_state->lock_.lock();
+    if (!target_state->lock_.reader_try_lock()) {
+      continue;
+    }
 
     // Dig down to our level
     PROFILE_STEALING("Go to our level")
-                    abstract_task* current_task = target_state->root_task_;
+    abstract_task *current_task = target_state->root_task_;
     while (current_task != nullptr && current_task->depth() < depth()) {
-                        current_task = current_task->child_task_;
+      current_task = current_task->child();
     }
     PROFILE_END_BLOCK
 
@@ -41,12 +46,13 @@ namespace pls {
           current_task->depth_ == depth_) {
         if (internal_stealing(current_task)) {
           // internal steal was a success, hand it back to the internal scheduler
-                                target_state->lock_.unlock();
+          target_state->lock_.reader_unlock();
+          backoff.reset();
           return true;
         }
 
         // No success, we need to steal work from a deeper level using 'top level task stealing'
-                            current_task = current_task->child_task_;
+        current_task = current_task->child();
       }
     }
     PROFILE_END_BLOCK;
@@ -58,19 +64,22 @@ namespace pls {
     while (current_task != nullptr) {
       auto lock = &target_state->lock_;
       if (current_task->split_task(lock)) {
-                            // internal steal was no success (we did a top level task steal)
+        // top level steal was a success (we did a top level task steal)
+        backoff.reset();
         return false;
       }
 
       current_task = current_task->child_task_;
     }
     PROFILE_END_BLOCK;
-                    target_state->lock_.unlock();
+    target_state->lock_.reader_unlock();
   }
 
   // internal steal was no success
+  backoff.do_backoff();
   return false;
-            };
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/scheduling/fork_join_task.cpp

@@ -4,51 +4,39 @@
 #include "pls/internal/scheduling/fork_join_task.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            fork_join_sub_task::fork_join_sub_task():
-                data_structures::deque_item{},
+namespace internal {
+namespace scheduling {
+
+fork_join_sub_task::fork_join_sub_task() :
     ref_count_{0},
     parent_{nullptr},
     tbb_task_{nullptr},
-                stack_state_{nullptr} {}
+    deque_state_{0} {}
 
-            fork_join_sub_task::fork_join_sub_task(const fork_join_sub_task& other):
-                data_structures::deque_item(other),
+fork_join_sub_task::fork_join_sub_task(const fork_join_sub_task &other) :
     ref_count_{0},
-                parent_{nullptr},
-                tbb_task_{nullptr},
-                stack_state_{nullptr} {}
+    parent_{other.parent_},
+    tbb_task_{other.tbb_task_},
+    deque_state_{other.deque_state_} {}
 
-            void fork_join_sub_task::execute()  {
+void fork_join_sub_task::execute() {
   PROFILE_WORK_BLOCK("execute sub_task")
+  auto last_executing = tbb_task_->currently_executing_;
   tbb_task_->currently_executing_ = this;
   execute_internal();
-                tbb_task_->currently_executing_ = nullptr;
+  tbb_task_->currently_executing_ = last_executing;
   PROFILE_END_BLOCK
   wait_for_all();
 
   if (parent_ != nullptr) {
     parent_->ref_count_--;
   }
-            }
-
-            void fork_join_sub_task::spawn_child_internal(fork_join_sub_task* sub_task) {
-                // Keep our refcount up to date
-                ref_count_++;
-
-                // Assign forced values
-                sub_task->parent_ = this;
-                sub_task->tbb_task_ = tbb_task_;
-                sub_task->stack_state_ = tbb_task_->my_stack_->save_state();
-
-                tbb_task_->deque_.push_tail(sub_task);
-            }
+}
 
-            void fork_join_sub_task::wait_for_all() {
+void fork_join_sub_task::wait_for_all() {
   while (ref_count_ > 0) {
     PROFILE_STEALING("get local sub task")
-                    fork_join_sub_task* local_task = tbb_task_->get_local_sub_task();
+    fork_join_sub_task *local_task = tbb_task_->get_local_sub_task();
     PROFILE_END_BLOCK
     if (local_task != nullptr) {
       local_task->execute();
@@ -63,20 +51,24 @@ namespace pls {
       }
     }
   }
-                tbb_task_->my_stack_->reset_state(stack_state_);
-            }
+  tbb_task_->deque_.release_memory_until(deque_state_);
+}
 
-            fork_join_sub_task* fork_join_task::get_local_sub_task() {
+fork_join_sub_task *fork_join_task::get_local_sub_task() {
   return deque_.pop_tail();
-            }
+}
 
-            fork_join_sub_task* fork_join_task::get_stolen_sub_task() {
+fork_join_sub_task *fork_join_task::get_stolen_sub_task() {
   return deque_.pop_head();
-            }
+}
 
-            bool fork_join_task::internal_stealing(abstract_task* other_task) {
+fork_join_sub_task *fork_join_sub_task::current() {
+  return dynamic_cast<fork_join_task *>(scheduler::current_task())->currently_executing();
+}
+
+bool fork_join_task::internal_stealing(abstract_task *other_task) {
   PROFILE_STEALING("fork_join_task::internal_stealin")
-                auto cast_other_task = reinterpret_cast<fork_join_task*>(other_task);
+  auto cast_other_task = reinterpret_cast<fork_join_task *>(other_task);
 
   auto stolen_sub_task = cast_other_task->get_stolen_sub_task();
   if (stolen_sub_task == nullptr) {
@@ -84,51 +76,54 @@ namespace pls {
   } else {
     // Make sub-task belong to our fork_join_task instance
     stolen_sub_task->tbb_task_ = this;
-                    stolen_sub_task->stack_state_ = my_stack_->save_state();
+    stolen_sub_task->deque_state_ = deque_.save_state();
     // We will execute this next without explicitly moving it onto our stack storage
     last_stolen_ = stolen_sub_task;
 
     return true;
   }
-            }
+}
 
-            bool fork_join_task::split_task(base::spin_lock* lock) {
+bool fork_join_task::split_task(base::swmr_spin_lock *lock) {
   PROFILE_STEALING("fork_join_task::split_task")
-                fork_join_sub_task* stolen_sub_task = get_stolen_sub_task();
+  fork_join_sub_task *stolen_sub_task = get_stolen_sub_task();
   if (stolen_sub_task == nullptr) {
     return false;
   }
   fork_join_task task{stolen_sub_task, this->unique_id()};
 
   // In success case, unlock.
-                // TODO: this locking is complicated and error prone.
-                lock->unlock();
+  lock->reader_unlock();
 
   scheduler::execute_task(task, depth());
   return true;
-            }
+}
 
-            void fork_join_task::execute() {
+void fork_join_task::execute() {
   PROFILE_WORK_BLOCK("execute fork_join_task");
 
   // Bind this instance to our OS thread
-                my_stack_ = base::this_thread::state<thread_state>()->task_stack_;
+  // TODO: See if we did this right
+  // my_stack_ = base::this_thread::state<thread_state>()->task_stack_;
+  deque_.reset_base_pointer();
+
   root_task_->tbb_task_ = this;
-                root_task_->stack_state_ = my_stack_->save_state();
+  root_task_->deque_state_ = deque_.save_state();
 
   // Execute it on our OS thread until its finished
   root_task_->execute();
-            }
+}
 
-            fork_join_sub_task* fork_join_task::currently_executing() const { return currently_executing_; }
+fork_join_sub_task *fork_join_task::currently_executing() const { return currently_executing_; }
 
-            fork_join_task::fork_join_task(fork_join_sub_task* root_task, const abstract_task::id& id):
+fork_join_task::fork_join_task(fork_join_sub_task *root_task,
+                               const abstract_task::id &id) :
     abstract_task{0, id},
     root_task_{root_task},
     currently_executing_{nullptr},
-                my_stack_{nullptr},
-                deque_{},
-                last_stolen_{nullptr} {};
-        }
-    }
+    deque_{base::this_thread::state<thread_state>()->task_stack_},
+    last_stolen_{nullptr} {}
+
+}
+}
 }

lib/pls/src/internal/scheduling/root_task.cpp

 #include "pls/internal/scheduling/root_task.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
-        }
-    }
+}
+}
 }

lib/pls/src/internal/scheduling/run_on_n_threads_task.cpp

 #include "pls/internal/scheduling/run_on_n_threads_task.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
-        }
-    }
+}
+}
 }

lib/pls/src/internal/scheduling/scheduler.cpp

@@ -2,9 +2,10 @@
 #include "pls/internal/base/error_handling.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            scheduler::scheduler(scheduler_memory* memory, const unsigned int num_threads):
+namespace internal {
+namespace scheduling {
+
+scheduler::scheduler(scheduler_memory *memory, const unsigned int num_threads) :
     num_threads_{num_threads},
     memory_{memory},
     sync_barrier_{num_threads + 1},
@@ -15,16 +16,17 @@ namespace pls {
 
   for (unsigned int i = 0; i < num_threads_; i++) {
     // Placement new is required, as the memory of `memory_` is not required to be initialized.
-                    new((void*)memory_->thread_state_for(i)) thread_state{this, memory_->task_stack_for(i), i};
-                    new ((void*)memory_->thread_for(i))base::thread<void(*)(), thread_state>(&worker_routine, memory_->thread_state_for(i));
-                }
+    new((void *) memory_->thread_state_for(i)) thread_state{this, memory_->task_stack_for(i), i};
+    new((void *) memory_->thread_for(i))base::thread<void (*)(), thread_state>(&worker_routine,
+                                                                               memory_->thread_state_for(i));
   }
+}
 
-            scheduler::~scheduler() {
+scheduler::~scheduler() {
   terminate();
-            }
+}
 
-            void worker_routine() {
+void worker_routine() {
   auto my_state = base::this_thread::state<thread_state>();
 
   while (true) {
@@ -40,9 +42,9 @@ namespace pls {
 
     my_state->scheduler_->sync_barrier_.wait();
   }
-            }
+}
 
-            void scheduler::terminate(bool wait_for_workers) {
+void scheduler::terminate(bool wait_for_workers) {
   if (terminated_) {
     return;
   }
@@ -55,7 +57,8 @@ namespace pls {
       memory_->thread_for(i)->join();
     }
   }
-            }
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/scheduling/scheduler_memory.cpp

 #include "pls/internal/scheduling/scheduler_memory.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            malloc_scheduler_memory::malloc_scheduler_memory(const size_t num_threads, const size_t memory_per_stack):
+namespace internal {
+namespace scheduling {
+
+malloc_scheduler_memory::malloc_scheduler_memory(const size_t num_threads, const size_t memory_per_stack) :
     num_threads_{num_threads} {
-                threads_ = reinterpret_cast<aligned_thread *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread)));
-                thread_states_ = reinterpret_cast<aligned_thread_state *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread_state)));
+  threads_ =
+      reinterpret_cast<aligned_thread *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread)));
+  thread_states_ = reinterpret_cast<aligned_thread_state *>(base::alignment::allocate_aligned(
+      num_threads * sizeof(aligned_thread_state)));
 
-                task_stacks_ = reinterpret_cast<aligned_aligned_stack *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_aligned_stack)));
-                task_stacks_memory_ = reinterpret_cast<char**>(base::alignment::allocate_aligned(num_threads * sizeof(char*)));
+  task_stacks_ = reinterpret_cast<aligned_aligned_stack *>(base::alignment::allocate_aligned(
+      num_threads * sizeof(aligned_aligned_stack)));
+  task_stacks_memory_ = reinterpret_cast<char **>(base::alignment::allocate_aligned(num_threads * sizeof(char *)));
   for (size_t i = 0; i < num_threads_; i++) {
-                    task_stacks_memory_[i] = reinterpret_cast<char*>(base::alignment::allocate_aligned(memory_per_stack));
-                    new ((void*)task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i], memory_per_stack);
-                }
+    task_stacks_memory_[i] = reinterpret_cast<char *>(base::alignment::allocate_aligned(memory_per_stack));
+    new((void *) task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i], memory_per_stack);
   }
+}
 
-            malloc_scheduler_memory::~malloc_scheduler_memory() {
+malloc_scheduler_memory::~malloc_scheduler_memory() {
   free(threads_);
   free(thread_states_);
 
@@ -25,7 +29,8 @@ namespace pls {
   }
   free(task_stacks_);
   free(task_stacks_memory_);
-            }
-        }
-    }
+}
+
+}
+}
 }

lib/pls/src/internal/scheduling/thread_state.cpp

 #include "pls/internal/scheduling/thread_state.h"
 
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
-        }
-    }
+}
+}
 }

test/CMakeLists.txt

 add_executable(tests
         main.cpp
-        base_tests.cpp scheduling_tests.cpp data_structures_test.cpp)
+        data_structures_test.cpp)
 target_link_libraries(tests catch2 pls)

test/base_tests.cpp

@@ -13,7 +13,7 @@ static bool base_tests_visited;
 static int base_tests_local_value_one;
 static vector<int> base_tests_local_value_two;
 
-TEST_CASE( "thread creation and joining", "[internal/data_structures/thread.h]") {
+TEST_CASE("thread creation and joining", "[internal/data_structures/thread.h]") {
   base_tests_visited = false;
   auto t1 = start_thread([]() { base_tests_visited = true; });
   t1.join();
@@ -21,7 +21,7 @@ TEST_CASE( "thread creation and joining", "[internal/data_structures/thread.h]")
   REQUIRE(base_tests_visited);
 }
 
-TEST_CASE( "thread state", "[internal/data_structures/thread.h]") {
+TEST_CASE("thread state", "[internal/data_structures/thread.h]") {
   int state_one = 1;
   vector<int> state_two{1, 2};
 
@@ -36,12 +36,12 @@ TEST_CASE( "thread state", "[internal/data_structures/thread.h]") {
 
 int base_tests_shared_counter;
 
-TEST_CASE( "spinlock protects concurrent counter", "[internal/data_structures/spinlock.h]") {
+TEST_CASE("spinlock protects concurrent counter", "[internal/data_structures/spinlock.h]") {
   constexpr int num_iterations = 1000000;
   base_tests_shared_counter = 0;
   spin_lock lock{};
 
-    SECTION( "lock can be used by itself" ) {
+  SECTION("lock can be used by itself") {
     auto t1 = start_thread([&]() {
       for (int i = 0; i < num_iterations; i++) {
         lock.lock();
@@ -63,7 +63,7 @@ TEST_CASE( "spinlock protects concurrent counter", "[internal/data_structures/sp
     REQUIRE(base_tests_shared_counter == 0);
   }
 
-    SECTION( "lock can be used with std::lock_guard" ) {
+  SECTION("lock can be used with std::lock_guard") {
     auto t1 = start_thread([&]() {
       for (int i = 0; i < num_iterations; i++) {
         std::lock_guard<spin_lock> my_lock{lock};

test/data_structures_test.cpp

@@ -4,6 +4,7 @@
 
 #include <pls/internal/data_structures/aligned_stack.h>
 #include <pls/internal/data_structures/deque.h>
+#include <pls/internal/data_structures/work_stealing_deque.h>
 
 #include <vector>
 #include <mutex>
@@ -12,13 +13,12 @@ using namespace pls::internal::data_structures;
 using namespace pls::internal::base;
 using namespace std;
 
-
-TEST_CASE( "aligned stack stores objects correctly", "[internal/data_structures/aligned_stack.h]") {
+TEST_CASE("aligned stack stores objects correctly", "[internal/data_structures/aligned_stack.h]") {
   constexpr long data_size = 1024;
   char data[data_size];
   aligned_stack stack{data, data_size};
 
-    SECTION( "stack correctly pushes sub linesize objects" ) {
+  SECTION("stack correctly pushes sub linesize objects") {
     std::array<char, 5> small_data_one{'a', 'b', 'c', 'd', 'e'};
     std::array<char, 64> small_data_two{};
     std::array<char, 1> small_data_three{'A'};
@@ -32,7 +32,7 @@ TEST_CASE( "aligned stack stores objects correctly", "[internal/data_structures/
     REQUIRE(reinterpret_cast<std::uintptr_t>(pointer_three) % system_details::CACHE_LINE_SIZE == 0);
   }
 
-    SECTION( "stack correctly pushes above linesize objects" ) {
+  SECTION("stack correctly pushes above linesize objects") {
     std::array<char, 5> small_data_one{'a', 'b', 'c', 'd', 'e'};
     std::array<char, system_details::CACHE_LINE_SIZE + 10> big_data_one{};
 
@@ -43,7 +43,7 @@ TEST_CASE( "aligned stack stores objects correctly", "[internal/data_structures/
     REQUIRE(reinterpret_cast<std::uintptr_t>(small_pointer_one) % system_details::CACHE_LINE_SIZE == 0);
   }
 
-    SECTION( "stack correctly stores and retrieves objects" ) {
+  SECTION("stack correctly stores and retrieves objects") {
     std::array<char, 5> data_one{'a', 'b', 'c', 'd', 'e'};
 
     stack.push(data_one);
@@ -52,7 +52,7 @@ TEST_CASE( "aligned stack stores objects correctly", "[internal/data_structures/
     REQUIRE(retrieved_data == std::array<char, 5>{'a', 'b', 'c', 'd', 'e'});
   }
 
-    SECTION( "stack can push and pop multiple times with correct alignment" ) {
+  SECTION("stack can push and pop multiple times with correct alignment") {
     std::array<char, 5> small_data_one{'a', 'b', 'c', 'd', 'e'};
     std::array<char, 64> small_data_two{};
     std::array<char, 1> small_data_three{'A'};
@@ -76,15 +76,15 @@ TEST_CASE( "aligned stack stores objects correctly", "[internal/data_structures/
   }
 }
 
-TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]") {
-    class my_item: public deque_item {
+TEST_CASE("deque stores objects correctly", "[internal/data_structures/deque.h]") {
+  class my_item : public deque_item {
 
   };
 
   deque<my_item> deque;
   my_item one, two, three;
 
-    SECTION( "add and remove items form the tail" ) {
+  SECTION("add and remove items form the tail") {
     deque.push_tail(&one);
     deque.push_tail(&two);
     deque.push_tail(&three);
@@ -94,7 +94,7 @@ TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]
     REQUIRE(deque.pop_tail() == &one);
   }
 
-    SECTION( "handles getting empty by popping the tail correctly" ) {
+  SECTION("handles getting empty by popping the tail correctly") {
     deque.push_tail(&one);
     REQUIRE(deque.pop_tail() == &one);
 
@@ -102,7 +102,7 @@ TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]
     REQUIRE(deque.pop_tail() == &two);
   }
 
-    SECTION( "remove items form the head" ) {
+  SECTION("remove items form the head") {
     deque.push_tail(&one);
     deque.push_tail(&two);
     deque.push_tail(&three);
@@ -112,7 +112,7 @@ TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]
     REQUIRE(deque.pop_head() == &three);
   }
 
-    SECTION( "handles getting empty by popping the head correctly" ) {
+  SECTION("handles getting empty by popping the head correctly") {
     deque.push_tail(&one);
     REQUIRE(deque.pop_head() == &one);
 
@@ -120,7 +120,7 @@ TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]
     REQUIRE(deque.pop_head() == &two);
   }
 
-    SECTION( "handles getting empty by popping the head and tail correctly" ) {
+  SECTION("handles getting empty by popping the head and tail correctly") {
     deque.push_tail(&one);
     REQUIRE(deque.pop_tail() == &one);
 
@@ -131,3 +131,90 @@ TEST_CASE( "deque stores objects correctly", "[internal/data_structures/deque.h]
     REQUIRE(deque.pop_tail() == &three);
   }
 }
+
+TEST_CASE("work stealing deque stores objects correctly", "[internal/data_structures/aligned_stack.h]") {
+  constexpr long data_size = 2 << 14;
+  char data[data_size];
+  aligned_stack stack{data, data_size};
+  work_stealing_deque<int> deque{&stack};
+
+  int one = 1, two = 2, three = 3, four = 4;
+
+  SECTION("add and remove items form the tail") {
+    deque.push_tail(one);
+    deque.push_tail(two);
+    deque.push_tail(three);
+
+    REQUIRE(*deque.pop_tail() == three);
+    REQUIRE(*deque.pop_tail() == two);
+    REQUIRE(*deque.pop_tail() == one);
+  }
+
+  SECTION("handles getting empty by popping the tail correctly") {
+    deque.push_tail(one);
+    REQUIRE(*deque.pop_tail() == one);
+
+    deque.push_tail(two);
+    REQUIRE(*deque.pop_tail() == two);
+  }
+
+  SECTION("remove items form the head") {
+    deque.push_tail(one);
+    deque.push_tail(two);
+    deque.push_tail(three);
+
+    REQUIRE(*deque.pop_head() == one);
+    REQUIRE(*deque.pop_head() == two);
+    REQUIRE(*deque.pop_head() == three);
+  }
+
+  SECTION("handles getting empty by popping the head correctly") {
+    deque.push_tail(one);
+    REQUIRE(*deque.pop_head() == one);
+
+    deque.push_tail(two);
+    REQUIRE(*deque.pop_head() == two);
+  }
+
+  SECTION("handles getting empty by popping the head and tail correctly") {
+    deque.push_tail(one);
+    REQUIRE(*deque.pop_tail() == one);
+
+    deque.push_tail(two);
+    REQUIRE(*deque.pop_head() == two);
+
+    deque.push_tail(three);
+    REQUIRE(*deque.pop_tail() == three);
+  }
+
+  SECTION("handles jumps bigger 1 correctly") {
+    deque.push_tail(one);
+    deque.push_tail(two);
+    REQUIRE(*deque.pop_tail() == two);
+
+    deque.push_tail(three);
+    deque.push_tail(four);
+    REQUIRE(*deque.pop_head() == one);
+    REQUIRE(*deque.pop_head() == three);
+    REQUIRE(*deque.pop_head() == four);
+  }
+
+  SECTION("handles stack reset 1 correctly when emptied by tail") {
+    deque.push_tail(one);
+    deque.push_tail(two);
+    auto tmp_result = deque.pop_tail();
+    REQUIRE(*tmp_result == two);
+
+    deque.release_memory_until(tmp_result);
+    REQUIRE(*deque.pop_tail() == one);
+
+    deque.push_tail(three);
+    deque.push_tail(four);
+    REQUIRE(*deque.pop_head() == three);
+    REQUIRE(*deque.pop_tail() == four);
+  }
+
+  SECTION("synces correctly") {
+
+  }
+}

test/scheduling_tests.cpp

@@ -4,11 +4,11 @@
 
 using namespace pls;
 
-class once_sub_task: public fork_join_sub_task {
-    std::atomic<int>* counter_;
+class once_sub_task : public fork_join_sub_task {
+  std::atomic<int> *counter_;
   int children_;
 
-protected:
+ protected:
   void execute_internal() override {
     (*counter_)++;
     for (int i = 0; i < children_; i++) {
@@ -16,38 +16,37 @@ protected:
     }
   }
 
-public:
-    explicit once_sub_task(std::atomic<int>* counter, int children):
+ public:
+  explicit once_sub_task(std::atomic<int> *counter, int children) :
       fork_join_sub_task(),
       counter_{counter},
       children_{children} {}
 };
 
-class force_steal_sub_task: public fork_join_sub_task {
-    std::atomic<int>* parent_counter_;
-    std::atomic<int>* overall_counter_;
+class force_steal_sub_task : public fork_join_sub_task {
+  std::atomic<int> *parent_counter_;
+  std::atomic<int> *overall_counter_;
 
-protected:
+ protected:
   void execute_internal() override {
     (*overall_counter_)--;
     if (overall_counter_->load() > 0) {
       std::atomic<int> counter{1};
       spawn_child(force_steal_sub_task(&counter, overall_counter_));
-            while (counter.load() > 0)
-                ; // Spin...
+      while (counter.load() > 0); // Spin...
     }
 
     (*parent_counter_)--;
   }
 
-public:
-    explicit force_steal_sub_task(std::atomic<int>* parent_counter, std::atomic<int>* overall_counter):
+ public:
+  explicit force_steal_sub_task(std::atomic<int> *parent_counter, std::atomic<int> *overall_counter) :
       fork_join_sub_task(),
       parent_counter_{parent_counter},
       overall_counter_{overall_counter} {}
 };
 
-TEST_CASE( "tbb task are scheduled correctly", "[internal/scheduling/fork_join_task.h]") {
+TEST_CASE("tbb task are scheduled correctly", "[internal/scheduling/fork_join_task.h]") {
   malloc_scheduler_memory my_scheduler_memory{8, 2 << 12};
 
   SECTION("tasks are executed exactly once") {
@@ -56,7 +55,7 @@ TEST_CASE( "tbb task are scheduled correctly", "[internal/scheduling/fork_join_t
     int total_tasks = 1 + 4 + 4 * 3 + 4 * 3 * 2 + 4 * 3 * 2 * 1;
     std::atomic<int> counter{0};
 
-        my_scheduler.perform_work([&] (){
+    my_scheduler.perform_work([&]() {
       once_sub_task sub_task{&counter, start_counter};
       fork_join_task task{&sub_task, unique_id::create(42)};
       scheduler::execute_task(task);
@@ -68,7 +67,7 @@ TEST_CASE( "tbb task are scheduled correctly", "[internal/scheduling/fork_join_t
 
   SECTION("tasks can be stolen") {
     scheduler my_scheduler{&my_scheduler_memory, 8};
-        my_scheduler.perform_work([&] (){
+    my_scheduler.perform_work([&]() {
       std::atomic<int> dummy_parent{1}, overall_counter{8};
       force_steal_sub_task sub_task{&dummy_parent, &overall_counter};
       fork_join_task task{&sub_task, unique_id::create(42)};