Commands return exit code 2 while process is terminating

Question

I have a long-running PHP process which is handling signals. The signals are handled at the end of each "iteration" using pcntl_signal_dispatch(), along with some other tasks. Some of these tasks run command line operations, such as find.

As soon as the process receives a SIGINT (with Ctrl+C), whether before or after the signal handling by the process, all the command line operations start failing and return exit code 2.

What's going on? I doubt there is any way to fix it, but I would like to understand what is causing this issue.

Edit: Here is a code sample to reproduce the issue:

echo "START\n";

$run = true;
pcntl_signal(SIGINT, function() use ($run) {
    $run = false;
});

while ($run) {
    $command = 'sleep 1 && find . -name "*.md"';
    exec($command, $result, $exitCode);

    if ($exitCode !== 0 || !isset($result[0])) {
        throw new \RuntimeException("Command failed with exit code '{$exitCode}'.");
    }

    pcntl_signal_dispatch();
}

echo "END\n";
die;

I am completely unable to get even this small script to end properly (with echo "END\n"; die;); it always ends with the RuntimeException.

It's as if the signals were also interrupting the commands launched from the process. Maybe the signals are being sent to the process as well as all its current and future children?

If that is the case, is there anything I can do to handle this situation better? I could set some kind of "global" variable indicating that a signal has been caught and that commands shouldn't be run from that point, but that's a bit messy and wouldn't work for the commands that are run during the interval between the signal and my call to pcntl_signal_dispatch().

Commands return exit code 2 while process is terminating

0 Answers0