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#include <Processors/Executors/ExecutorTasks.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
}
void ExecutorTasks::finish()
{
{
std::lock_guard lock(mutex);
finished = true;
async_task_queue.finish();
}
std::lock_guard guard(executor_contexts_mutex);
for (auto & context : executor_contexts)
context->wakeUp();
}
void ExecutorTasks::rethrowFirstThreadException()
{
for (auto & executor_context : executor_contexts)
executor_context->rethrowExceptionIfHas();
}
void ExecutorTasks::tryWakeUpAnyOtherThreadWithTasks(ExecutionThreadContext & self, std::unique_lock<std::mutex> & lock)
{
if (!task_queue.empty() && !threads_queue.empty() && !finished)
{
size_t next_thread = self.thread_number + 1 >= use_threads ? 0 : (self.thread_number + 1);
auto thread_to_wake = task_queue.getAnyThreadWithTasks(next_thread);
if (threads_queue.has(thread_to_wake))
threads_queue.pop(thread_to_wake);
else
thread_to_wake = threads_queue.popAny();
if (thread_to_wake >= use_threads)
throw Exception(ErrorCodes::LOGICAL_ERROR, "Non-empty queue without allocated thread");
lock.unlock();
executor_contexts[thread_to_wake]->wakeUp();
}
}
void ExecutorTasks::tryGetTask(ExecutionThreadContext & context)
{
{
std::unique_lock lock(mutex);
/// Try get async task assigned to this thread or any other task from queue.
if (auto * async_task = context.tryPopAsyncTask())
{
context.setTask(async_task);
--num_waiting_async_tasks;
}
else if (!task_queue.empty())
context.setTask(task_queue.pop(context.thread_number));
/// Task found.
if (context.hasTask())
{
/// We have to wake up at least one thread if there are pending tasks.
/// That thread will wake up other threads during its `tryGetTask()` call if any.
tryWakeUpAnyOtherThreadWithTasks(context, lock);
return;
}
/// This thread has no tasks to do and is going to wait.
/// Finish execution if this was the last active thread.
if (threads_queue.size() + 1 == use_threads && async_task_queue.empty() && num_waiting_async_tasks == 0)
{
lock.unlock();
finish();
return;
}
#if defined(OS_LINUX)
if (num_threads == 1)
{
/// If we execute in single thread, wait for async tasks here.
auto res = async_task_queue.wait(lock);
if (!res)
{
if (finished)
return;
throw Exception(ErrorCodes::LOGICAL_ERROR, "Empty task was returned from async task queue");
}
context.setTask(static_cast<ExecutingGraph::Node *>(res.data));
return;
}
#endif
/// Enqueue thread into stack of waiting threads.
threads_queue.push(context.thread_number);
}
context.wait(finished);
}
void ExecutorTasks::pushTasks(Queue & queue, Queue & async_queue, ExecutionThreadContext & context)
{
context.setTask(nullptr);
/// Take local task from queue if has one.
if (!queue.empty() && !context.hasAsyncTasks())
{
context.setTask(queue.front());
queue.pop();
}
if (!queue.empty() || !async_queue.empty())
{
std::unique_lock lock(mutex);
#if defined(OS_LINUX)
while (!async_queue.empty() && !finished)
{
int fd = async_queue.front()->processor->schedule();
async_task_queue.addTask(context.thread_number, async_queue.front(), fd);
async_queue.pop();
}
#endif
while (!queue.empty() && !finished)
{
task_queue.push(queue.front(), context.thread_number);
queue.pop();
}
/// Wake up at least one thread that will wake up other threads if required
tryWakeUpAnyOtherThreadWithTasks(context, lock);
}
}
void ExecutorTasks::init(size_t num_threads_, size_t use_threads_, bool profile_processors, bool trace_processors, ReadProgressCallback * callback)
{
num_threads = num_threads_;
use_threads = use_threads_;
threads_queue.init(num_threads);
task_queue.init(num_threads);
{
std::lock_guard guard(executor_contexts_mutex);
executor_contexts.reserve(num_threads);
for (size_t i = 0; i < num_threads; ++i)
executor_contexts.emplace_back(std::make_unique<ExecutionThreadContext>(i, profile_processors, trace_processors, callback));
}
}
void ExecutorTasks::fill(Queue & queue)
{
std::lock_guard lock(mutex);
size_t next_thread = 0;
while (!queue.empty())
{
task_queue.push(queue.front(), next_thread);
queue.pop();
++next_thread;
/// It is important to keep queues empty for threads that are not started yet.
/// Otherwise that thread can be selected by `tryWakeUpAnyOtherThreadWithTasks()`, leading to deadlock.
if (next_thread >= use_threads)
next_thread = 0;
}
}
void ExecutorTasks::upscale(size_t use_threads_)
{
std::lock_guard lock(mutex);
if (use_threads < use_threads_)
use_threads = use_threads_;
}
void ExecutorTasks::processAsyncTasks()
{
#if defined(OS_LINUX)
{
/// Wait for async tasks.
std::unique_lock lock(mutex);
while (auto task = async_task_queue.wait(lock))
{
auto * node = static_cast<ExecutingGraph::Node *>(task.data);
executor_contexts[task.thread_num]->pushAsyncTask(node);
++num_waiting_async_tasks;
if (threads_queue.has(task.thread_num))
{
threads_queue.pop(task.thread_num);
executor_contexts[task.thread_num]->wakeUp();
}
}
}
#endif
}
}
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