Question

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Using C/Pthreads: do shared variables need to be volatile?

In Linux/C: Do the global variables shared between threads need to be declared volatile (assume the variable get modified in one of the threads)?

What all situations do I need to declare a variable as volatile in threads?

Answer 1

If you are using pthreads, then no – volatile is neither necessary nor sufficient for correct synchronisation. If your accesses to the global variable are properly protected by a mutex (or another synchronisation primitive), then you can simply declare them as ordinary variables.