不使用条件变量来唤醒线程的最快方法 [英] fastest way to wake up a thread without using condition variable

问题描述

我正在尝试通过设置后台线程来解决一个特定任务来加速一段代码.当需要解决我的任务时，我想唤醒这些线程，执行此工作，然后再次阻止它们等待下一个任务.任务总是一样的.

I am trying to speed up a piece of code by having background threads already setup to solve one specific task. When it is time to solve my task I would like to wake up these threads, do the job and block them again waiting for the next task. The task is always the same.

我尝试使用条件变量(以及需要与它们一起使用的互斥体)，但是最终我减慢了代码的速度，而不是加快了代码的速度.主要是因为对所有必需功能的调用非常昂贵(pthread_cond_wait/pthread_cond_signal/pthread_mutex_lock/pthread_mutex_unlock).

I tried using condition variables (and mutex that need to go with them), but I ended up slowing my code down instead of speeding it up; mostly it happened because the calls to all needed functions are very expensive (pthread_cond_wait/pthread_cond_signal/pthread_mutex_lock/pthread_mutex_unlock).

使用线程池(我也没有)是没有意义的，因为它是一个过于通用的结构；在这里，我只想解决我的特定任务.根据实现的不同，我还将为队列支付性能损失.

There is no point in using a thread pool (that I don't have either) because it is a too generic construct; here I want to address only my specific task. Depending on the implementation I would also pay a performance penalty for the queue.

您是否建议不使用mutex或con_var快速唤醒?

Do you have any suggestion for a quick wake-up without using mutex or con_var?

我在考虑诸如定时器读取atomic variable之类的设置线程；如果将该变量设置为1，则线程将执行此工作；如果将其设置为0，它们将进入休眠状态几毫秒(我会从休眠状态开始，因为我想避免使用spinlocks，这对于CPU可能太昂贵了).你怎么看待这件事?任何建议都非常感谢.

I was thinking in setup threads like timers reading an atomic variable; if the variable is set to 1 the threads will do the job; if it is set to 0 they will go to sleep for few microseconds (I would start with microsecond sleep since I would like to avoid using spinlocks that might be too expensive for the CPU). What do you think about it? Any suggestion is very appreciated.

我正在使用Linux，gcc，C和C ++.

I am using Linux, gcc, C and C++.

推荐答案

这些功能应该很快.如果他们花费了大量时间，则很有可能尝试切换线程的次数过多.

These functions should be fast. If they are taking a large fraction of your time, it is quite possible that you are trying to switch threads too often.

尝试缓冲工作队列，并在大量工作积累后发送信号.

Try buffering up a work queue, and send the signal once a significant amount of work has accumulated.

如果由于任务之间的依赖关系而无法实现，那么您的应用程序根本不适合多线程处理.

If this is impossible due to dependencies between the tasks, then your application is not amenable to multithreading at all.

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