pcntl_wait not interrupted by SIGTERM
pcntl, php, sigterm
Solution
Your call to `pcntl_signal` specifies that the call should be restarted. Check the docs, `restart_syscalls` is `true` by default. So your call to `pcntl_signal` doesn't return until the child has terminated.
You have no call to flush. So PHP can hold the output of `echo` in a buffer.
So the behavior you are seeing is precisely the behavior you are requesting. The system call is restarted and the output is buffered.
Problem
According to the PHP docs for pcntl_wait, The wait function suspends execution of the current process until a child has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling function. However, when I run the following code and send SIGTERM to the parent process with `kill -s SIGTERM [pid]` the signal handler is only called after the child exits (i.e. I have to wait for the sleep to finish. Shouldn't `pcntl_wait()` be interrupted by SIGTERM? fork_test.php: ``` <?php declare(ticks = 1); function sig_handler($signo) { switch ($signo) { case SIGTERM: echo 'SIGTERM' . PHP_EOL; break; default: } } pcntl_signal(SIGTERM, 'sig_handler'); $pid = pcntl_fork(); if ($pid == -1) { die('could not fork'); } else if ($pid) { echo 'parent' . PHP_EOL; pcntl_wait($status); } else { echo 'child' . PHP_EOL; sleep(30); } ?> ``` Output (SIGTERM only appears after waiting 30 seconds): ``` $ php fork_test.php child parent SIGTERM ``` PHP Version => 5.3.3