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Wait and signal - std::condition_variable


 Basic functionality of condition variables - unsafe usage
 Using condition variables - the safe way

Detailed Description

Within multithreaded environments a system's reaction to some internal or external trigger may consist of a series of small steps executed by multiple threads. The steps may be executed at least partly in parallel. Within such a scenario there is often the need that a thread has to wait until some preprocessing has reached some state before he can start or proceed with his own processing.

A simple approach for the waiting thread might be polling: he repeatedly checks some shared data until he recognizes that the data's state allows to start his own processing. If the state is not yet reached he sleeps for a small time interval and then repeats the check.

The typical disadvantages of this approach are:

To avoid these disadvantages you can use