ladybird/Libraries/LibThreading/ThreadPool.cpp
Andreas Kling 8d234620bc LibThreading: Add ThreadPool class
Add a simple thread pool with a fixed number of worker threads and a
shared work queue. The pool is accessed via ThreadPool::the() which
lazily creates a singleton with 4 worker threads.

submit() enqueues a work item and signals a condvar. Worker threads
loop waiting on the condvar, picking up and executing work items.

Worker threads use 8 MiB stacks to match the main thread, since
the JS parser can build deep call stacks during off-thread parsing.
2026-03-06 13:06:05 +01:00

55 lines
1.2 KiB
C++

/*
* Copyright (c) 2026, the Ladybird developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibThreading/ThreadPool.h>
static constexpr size_t THREAD_COUNT = 4;
static constexpr size_t THREAD_STACK_SIZE = 8 * MiB;
namespace Threading {
ThreadPool& ThreadPool::the()
{
static ThreadPool* instance = new ThreadPool;
return *instance;
}
ThreadPool::ThreadPool()
{
for (size_t i = 0; i < THREAD_COUNT; ++i) {
auto name = ByteString::formatted("Pool/{}", i);
auto thread = Thread::construct(name, [this]() -> intptr_t {
return worker_thread_func();
});
thread->set_stack_size(THREAD_STACK_SIZE);
thread->start();
m_threads.append(move(thread));
}
}
intptr_t ThreadPool::worker_thread_func()
{
while (true) {
Function<void()> work;
{
MutexLocker locker(m_mutex);
m_condition.wait_while([this] { return m_work_queue.is_empty(); });
work = m_work_queue.dequeue();
}
work();
}
}
void ThreadPool::submit(Function<void()> work)
{
MutexLocker locker(m_mutex);
m_work_queue.enqueue(move(work));
m_condition.signal();
}
}