Is mq_send atomic?

Question

谁能告诉我，如果在mq_send执行期间多线程程序收到SIGSTOP信号，会发生什么情况？

Answer 1

The man page for mq_send indicates it is implemented on top of mq_timedsend , which is a system call in Linux. System calls are generally atomic in that they either succeed or they don't. If a system call is interrupted by a signal, the usual behavior is to return -1 and set errno to EINTR . It looks like mq_send has this behavior.

Basically, you should check for EINTR , and retry the call if it fails in this way. This is particularly important for system calls that may block like recv or select , since they have a higher chance of being interrupted.