The pthread_single_np function switches the process to a single-threaded mode, i.e., suspends all threads except the current. The semantics of this function is similar to pthread_suspend_all_np(3).
The pthread_multi_np function switches the process to a multi-threaded mode. The semantics of this function is similar to pthread_resume_all_np(3).
The pthread_single_np function is only available in
.Lb libc_r and
.Lb libpthread . This function is not implemented in
.Lb libthr .
The pthread_multi_np and pthread_single_np functions always return 0.