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在来自多个线程的阻塞套接字上使用send（）

[英]Using send() on a blocking socket from multiple threads

原文 2015-02-25 23:26:43 6 1 c++/ windows/ sockets

I have read that you are not supposed to use send() on a blocking socket from multiple threads, but I do not know why! 我读过您不应该在来自多个线程的阻塞套接字上使用send() ，但是我不知道为什么！ And if I want to use send() from multiple threads, is there anything I can do to allow it? 如果我想从多个线程中使用send() ，是否可以做些允许的事情？

I am using Windows. 我正在使用Windows。

1 个解决方案

The fundamental reason is that synchronous I/O functions use the handle object (sockets are implemented as handles) to keep track of whether the I/O is complete or not. 根本原因是同步I / O函数使用handle对象（将套接字实现为handle）来跟踪I / O是否完成。

The result is that if you try to send() to the same socket from multiple threads simultaneously, send() is liable to (a) hang or (b) exit before the I/O is actually complete, with catastrophic results. 结果是，如果您尝试同时从多个线程向同一套接字发送send（），则send（）可能会（a）挂起或（b）在I / O实际完成之前退出，从而导致灾难性的结果。

You can use a critical section to prevent the sends from overlapping, or have a designated thread that reads data to send from a queue. 您可以使用关键部分来防止发送重叠，或者使用指定的线程来读取要从队列发送的数据。

Note that this only applies if the sends are to the same socket. 请注意，这仅在发送到同一套接字的情况下适用。 Sending to different sockets simultaneously is fine. 同时发送到不同的套接字很好。