Revert to LFStack.

dbms/src/Processors/Executors/PipelineExecutor.cpp

@@ -437,7 +437,6 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
 
     Stopwatch total_time_watch;
     ExecutionState * state = nullptr;
-    std::queue<ExecutionState *> local_queue;
 
     auto prepare_processor = [&](UInt64 pid, Stack & children, Stack & parents)
     {
@@ -454,7 +453,7 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
         return false;
     };
 
-    using Queue = std::vector<ExecutionState *>;
+    using Queue = std::queue<ExecutionState *>;
 
     auto prepare_all_processors = [&](Queue & queue, Stack & stack, Stack & children, Stack & parents)
     {
@@ -464,7 +463,7 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
             stack.pop();
 
             if (prepare_processor(current_processor, children, parents))
-                queue.push_back(graph[current_processor].execution_state.get());
+                queue.push(graph[current_processor].execution_state.get());
         }
     };
 
@@ -475,19 +474,33 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
         /// Just travers graph and prepare any processor.
         while (!finished)
         {
-            if (!local_queue.empty())
+            auto pushed = task_queue.num_pushed.load();
+            bool found = false;
+
+            while (pushed > task_queue.num_popped.load())
             {
-                state = local_queue.front();
+                /// Fast branch.
-                local_queue.pop();
+                if (task_queue.pop(state))
+                {
+                    found = true;
                     break;
                 }
+            }
 
-            state = task_queue.pop(thread_num);
+            if (found)
-            if (state)
                 break;
 
             std::unique_lock lock(task_queue_mutex);
 
+            auto popped = task_queue.num_popped.load();
+
+//            if (!task_queue.empty())
+//            {
+//                state = task_queue.front();
+//                task_queue.pop();
+//                break;
+//            }
+
             ++num_waiting_threads;
 
             if (num_waiting_threads == num_threads)
@@ -500,7 +513,7 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
 
             task_queue_condvar.wait(lock, [&]()
             {
-                return finished || !task_queue.empty(thread_num) || !task_queue.empty(num_threads);
+                return finished || popped < task_queue.num_pushed.load();
             });
 
             --num_waiting_threads;
@@ -547,34 +560,26 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
                 /// Process all neighbours. Children will be on the top of stack, then parents.
                 prepare_all_processors(queue, children, children, parents);
 
-
+                if (!state && !queue.empty())
-                for (auto & exec_state : queue)
                 {
-                    auto stream = exec_state->processor->getStream();
+                    state = queue.front();
-
+                    queue.pop();
-                    if (stream == thread_num)
-                        local_queue.push(exec_state);
-                    else
-                        task_queue.push(exec_state);
                 }
 
-                queue.clear();
-
                 prepare_all_processors(queue, parents, parents, parents);
 
-                for (auto & exec_state : queue)
+                if (!queue.empty())
                 {
-                    auto stream = exec_state->processor->getStream();
+                    /// std::lock_guard lock(task_queue_mutex);
 
-                    if (stream == thread_num)
+                    while (!queue.empty() && !finished)
-                        local_queue.push(exec_state);
+                    {
-                    else
+                        task_queue.push(queue.front());
-                        task_queue.push(exec_state);
+                        queue.pop();
                     }
 
-                queue.clear();
-
                     task_queue_condvar.notify_all();
+                }
 
                 --num_processing_executors;
                 while (auto task = expand_pipeline_task.load())
@@ -597,8 +602,6 @@ void PipelineExecutor::executeSingleThread(size_t thread_num, size_t num_threads
 
 void PipelineExecutor::executeImpl(size_t num_threads)
 {
-    task_queue.init(num_threads);
-
     Stack stack;
 
     executor_contexts.reserve(num_threads);

dbms/src/Processors/Executors/PipelineExecutor.h

@@ -120,56 +120,26 @@ private:
 
     struct TaskQueue
     {
+        bool pop(ExecutionState *& state)
+        {
+            if (stack.pop(state))
+            {
+                num_popped.fetch_add(1);
+                return true;
+            }
+
+            return false;
+        }
+
         void push(ExecutionState * state)
         {
-            auto stream = state->processor->getStream();
+            stack.push(state);
-            if (stream >= queues.size())
+            num_pushed.fetch_add(1);
-                stream = queues.size() - 1;
-
-            std::lock_guard lg(*mutexes[stream]);
-            queues[stream].push(state);
         }
 
-        ExecutionState * pop(size_t stream)
+        lfs::LFStack<ExecutionState> stack;
-        {
+        std::atomic<UInt64> num_pushed {0};
-            {
+        std::atomic<UInt64> num_popped {0};
-                std::lock_guard lg(*mutexes[stream]);
-
-                if (!queues[stream].empty())
-                {
-                    auto res = queues[stream].front();
-                    queues[stream].pop();
-                    return res;
-                }
-            }
-
-            stream = queues.size() - 1;
-            if (!queues[stream].empty())
-            {
-                auto res = queues[stream].front();
-                queues[stream].pop();
-                return res;
-            }
-
-            return nullptr;
-        }
-
-        bool empty(size_t stream)
-        {
-            std::lock_guard lg(*mutexes[stream]);
-            return queues[stream].empty();
-        }
-
-        void init(size_t num_streams)
-        {
-            queues.resize(num_streams + 1);
-
-            for (size_t i = 0; i <= num_streams; ++i)
-                mutexes.emplace_back(std::make_unique<std::mutex>());
-        }
-
-        std::vector<std::queue<ExecutionState *>> queues;
-        std::vector<std::unique_ptr<std::mutex>> mutexes;
     };
 
     /// Queue with pointers to tasks. Each thread will concurrently read from it until finished flag is set.