From Wikipedia:
Operating systems schedule threads in one of two ways:
Preemptive multitasking is generally considered the superior approach, as it allows the operating system to determine when a context switch should occur. The disadvantage of preemptive multithreading is that the system may make a context switch at an inappropriate time, causing lock convoy, priority inversion or other negative effects, which may be avoided by cooperative multithreading.
Cooperative multithreading, on the other hand, relies on the threads themselves to relinquish control once they are at a stopping point. This can create problems if a thread is waiting for a resource to become available.
I wonder if in parallel computing (writing and running parallelized programs in OpenMP, OpenMPI, pThread), which of Cooperative multithreading and Preemptive multitasking is/are used, or does the way OS scheduling threads have nothing to do with the multi-process or multi-thread within a parallelized program?