CODEWITHSUNDEEP
clinux-kernelembeddedposixembedded-linux
linardni
linardni

Reputation: 3

Need to understand one usage of pthread_mutex_lock() and pthread_cond_wait() and pthread_cond_signal()

I need to understand one usage of pthread_mutex_lock() and pthread_cond_wait() and pthread_cond_signal().

I have seen a piece of code where a function, say for example, CallANumber() is invoked from main() and inside this CallANumber() function pthread_mutex_lock() is used along with pthread_cond_wait() and then release by pthread_mutex_unlock() and there is another function, say for example, WaitForResponse(), inside this function pthread_mutex_lock() along with pthread_cond_signal() has been called and released by pthread_mutex_unlock().

But I have not found any pthread_create() call inside the source base.

Is it possible to call Pthread_mutex_lock/unlock() and pthread_cond_wait/signal() APIs without a pthread_create() function getting never been called ?

Upvotes: 0

Views: 99

Answers (1)

Florian Weimer
Florian Weimer

Reputation: 33747

There are two reasons for using these functions in programs which are not multi-threaded:

  • The functions are called from generic code, perhaps in a library, and this library needs to perform synchronization in case the process is multi-threaded (which the library authors do not know). Without synchronization, the library might not work as expected in a multi-threaded program.

  • The synchronization happens across processes instead of threads, using process-shared mutexes and process-shared condition variables.

Upvotes: 3

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