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可以使用 boost::asio::thread_pool 而不是将 boost::asio::io_context 与 boost::thread::thread_group 结合使用吗？

[英]Can boost::asio::thread_pool be used instead of combining boost::asio::io_context with a boost::thread::thread_group?

原文 2018-09-18 00:21:07 5 2 c++/ boost-asio

I'm trying to clear up some confusion I have.我正在努力澄清我的一些困惑。 I stumbled over boost::asio::thread_pool and I thought that one could use to somehow automatically combine boost::asio::io_context and boost::thread::thread_group like is often suggested ( here or here ).我偶然发现了boost::asio::thread_pool并且我认为人们可以用某种方式自动组合boost::asio::io_context和boost::thread::thread_group就像经常建议的一样（ here或here ）。 It appears that this asio -specific pool can be used to post tasks to but, on the other hand, some networking types like resolver need to be passed an object io_context as a constructor parameter which thread_pool isn't and doesn't derive from.似乎这个特定于asio池可用于将任务post到，但另一方面，某些网络类型（如resolver需要传递一个对象io_context作为构造函数参数，而thread_pool不是也不是从中派生的。

2 个解决方案

Say you have a single io_context object, named ioc .假设您有一个名为ioc io_context对象。

You can create several threads, and call ioc.run() in each one of them.您可以创建多个线程，并在每个线程中调用ioc.run() 。 This is a blocking operation that blocks on epoll/select/kqueue.这是一个阻塞操作，阻塞在 epoll/select/kqueue 上。 Note that ioc is shareable, and by calling ioc.run() in several threads, they implicitly belong to a thread pool to be used by ioc .请注意， ioc是可共享的，并且通过在多个线程中调用ioc.run() ，它们隐式属于ioc使用的线程池。 Let's call this pool io_threadpool .我们称这个池为io_threadpool 。

Now create a separate pool of threads called compute , that do other things.现在创建一个名为compute的单独线程池，用于执行其他操作。 Here is what is possible:这是可能的：

You can use ioc in threads from both pools (except for a few, like restart() , which require that ioc is not actively running).您可以在来自两个池的线程中使用ioc （除了少数几个，如restart() ，它要求ioc不主动运行）。
You can make sync I/O calls from any thread.您可以从任何线程进行同步 I/O 调用。
You can invoke an async call like async_read( ..., handler) from any thread.您可以从任何线程调用async_read( ..., handler)等异步调用。 However, the handler is only invoked in one of the io_threadpool threads.但是，处理程序仅在io_threadpool线程之一中调用。
You can dispatch tasks in either thread pool, but if the task is not going to do any I/O, I expect it to be more efficient to dispatch it in the compute pool, because the system doesn't have to wake up the epoll() / kqueue() / select() call on which it is blocked.您可以在任一线程池中调度任务，但是如果任务不进行任何 I/O，我希望在计算池中调度它会更有效，因为系统不必唤醒epoll() / kqueue() / select()调用它被阻止。