CODEWITHSUNDEEP
clinuxmultithreadingsignals
tpotter01
tpotter01

Reputation: 79

Receiving SIGCHLD yet have spawned no child processes

I have a C program running on Linux 3.12. This program spawns several child processes. One of these processes spawns a thread that runs for a bit then terminates. While this child process is running it performs an epoll_wait(). Periodically, the epoll_wait returns with an EINTR error. I setup the child process to catch the signal doing this interruption and found it is a signal 17, which, according to everything I have read is a SIGCHLD. Thing is, the thread this child process spawned is still running. It did not terminate. I also thought that threads do not generate a SIGCHLD on termination.

Any thoughts on why my process may be getting a signal 17?

Upvotes: 0

Views: 1334

Answers (1)

tpotter01
tpotter01

Reputation: 79

The answer is a call to system(). This function in the code spawns a process to execute the shell command being passed in. The thread was calling system() to run some shell commands. When they finished the processes that was spawned ended and generated the SIGCHLD.

Upvotes: 1

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