英文:
Use boost thread_pool with boost steady_timer
问题
以下是翻译好的代码部分：
boost::asio::thread_pool thread_pool{};
boost::asio::steady_timer timer{thread_pool.get_executor(), std::chrono::seconds{1}};
timer.async_wait([](const boost::system::error_code& ec){
std::cout << "Task Completed" << std::endl;
});
请告诉我如果您需要进一步的信息。
英文:
I want to use execute a timer-based task with a pool of threads. I wrote the following code:
boost::asio::thread_pool thread_pool{};
boost::asio::steady_timer timer{thread_pool.get_executor(), std::chrono::seconds{1}};
timer.async_wait([](const boost::system::error_code&){
std::cout << "Task Completed" << std::endl;
});
Is this the correct way to achieve this? or should I be using an io_context and then run that in every thread of thread_group? From what I can find online is that io_context should be used for any io including timer-related tasks but then why does the above code compile with thread_pool? Since one can argue that using thread_pool provides a cleaner outlook is there any place I should use io_context?
答案1
得分: 1
> 这是实现这个的正确方法吗？
这是一个可以工作的正确方法。
> 或者我应该使用一个 io_context，然后在 thread_group 的每个线程中运行它？
你不应该。基本上是因为这几乎是完全相同的事情，但不太正确。使用自己的线程组时，你需要做一些工作来保持公平调度并正确处理异常。
> 由于有人可以争论使用 thread_pool 提供了更清晰的视角，我应该在哪里使用 io_context 吗？
实际上是一个很好的观点。当你不想要线程时，应该使用 io_context。有时你的平台不支持线程创建，线程调度引入了你想避免的非确定性，或者你只是不想在全局范围内有任何同步问题。例如：
int main() {
io_context ioc(1);
start_server(ioc);
ioc.run(); // 主线程
}
在概念上类似于：
int main() {
thread_pool ioc(1);
start_server(ioc);
ioc.join(); // 单独的线程
}
我通常写后者，也因为它可以减少对工作保护的需求（thread_pool 在内部持有执行器工作保护）。
英文:
> Is this the correct way to achieve this?
It is one correct way that can work
> or should I be using an io_context and then run that in every thread
> of thread_group?
You should not. Basically for the reason that it is almost exactly the same thing, but less correct. With your own thread-groups you have to do work to maintain fair scheduling and handle exceptions correctly.
> Since one can argue that using thread_pool provides a cleaner outlook is there any place I should use io_context?
Good point actually. You should use io_context when you don't want threads. Sometimes your platform doesn't support thread creation, thread scheduling introduces non-determinism you want to avoid, or you just don't want to have any synchronization issues even regarding globals. E.g.
int main() {
io_context ioc(1);
start_server(ioc);
ioc.run(); // main thread
}
Is conceptually similar to
int main() {
thread_pool ioc(1);
start_server(ioc);
ioc.join(); // separate thread
}
I liberally write the latter, also because it can reduce the need for work-guards (thread_pool hold an executor work guard internally).
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