process immediate exit after sigterm

[Ekstazi]

Some example code to reproduce

test.php

<?php
require __DIR__.'/vendor/autoload.php';

$onInterrupt = \Amp\Loop::onSignal(SIGINT, function ($reference){
    echo "sigterm\n";
    //\Amp\Loop::cancel($reference);
});
\Amp\Loop::run(function() use($onInterrupt ){
    $process = new \Amp\Process\Process("php test-process.php");
    $pid = yield $process->start();
    \Amp\ByteStream\pipe($process->getStdout(), \Amp\ByteStream\getStdout());
    \Amp\ByteStream\pipe($process->getStderr(), \Amp\ByteStream\getStderr());
    $code = yield $process->join();
    echo $code;
    if(file_exists("/proc/{$pid}")) {
        echo "Process still running\n";
    }
    yield new \Amp\Delayed(10000);
    \Amp\Loop::cancel($onInterrupt);
});

test-process.php

<?php
require __DIR__.'/vendor/autoload.php';

//pcntl_async_signals(true);
\Amp\Loop::onSignal(SIGINT, function (){
    echo "sigterm from parent\n";
});
echo "Start\n";
\Amp\Loop::repeat(100, function(){
    echo "test\n";
    sleep(1);
});
\Amp\Loop::run();
echo "exit\n";

Steps to reproduce

1. I start script test.php. Example output was:

   Start
   test
   test
   test

   Process list:

   26434 pts/7    S+     0:00 php ./test.php
   26435 pts/7    S+     0:00 sh -c { (php test-process.php) <&3 3<&- 3>/dev/null & } 3<&0;pid=$!; echo $pid >&3; wait $pid; RC=$?; echo $RC >&3; exit $RC
   26436 pts/7    S+     0:00 php test-process.php

2. I send sigint(ctrl+c) to script. Output was:

   ^C0Process still running
   sigterm from parent
   test
   sigterm

   Processs list:

   27301 pts/7    S+     0:00 php ./test.php
   27303 pts/7    S+     0:00 php test-process.php

3. I wait for script to finish. Output was:

   test
   test
   test
   test
   test
   test
   test
   test
   test
   test

   Actual behavior

   As you can see when sigint received php closed process wrapper (sh -c) and send sigint to test-process.php. amp/Process wait for process wrapper to finish but doesn't wait for test-process.php. But pipes will continue to work after that. The child process only killed after main process exit.

Expected behavior

Process::join only resolves when test-process.php finished/halted/cancelled.

[trowski]

I was not able to reproduce this on macOS, but I was able to reproduce this on Ubuntu. The sh process terminates in both, but on macOS join() does not resolve until the child PHP process exits, whereas on Ubuntu join() resolves as soon as the sh process ends.

[Ekstazi]

Thx for fix. But signals still broadcasted to child process. How i can prevent it ? I handled signals in my parent process and want to send it to child only from code.

[Ekstazi]

Also signal handling not worked after that fix. I changed test.php scrip:

<?php
require __DIR__.'/vendor/autoload.php';

\Amp\Loop::run(function(){
    $process = new \Amp\Process\Process("php test-process.php");
    $pid = yield $process->start();
    \Amp\ByteStream\pipe($process->getStdout(), \Amp\ByteStream\getStdout());
    \Amp\ByteStream\pipe($process->getStderr(), \Amp\ByteStream\getStderr());
    $onInterrupt = \Amp\Loop::onSignal(SIGINT, function ($reference) use ($process){
        echo "sigterm\n";
        yield new \Amp\Delayed(5000);
        echo "terminating child\n";
        $process->signal(SIGINT);
        \Amp\Loop::cancel($reference);
    });
    $code = yield $process->join();
    echo $code;
    if(file_exists("/proc/{$pid}")) {
        echo "Process still running\n";
    }
    yield new \Amp\Delayed(10000);
    \Amp\Loop::cancel($onInterrupt);
});

As you can see:

1. i started test-process.php
2. wait for sigint
3. if sigint received then wait 5s and send it child

As i can see sigint briadcasted on step 2 but i can't send it manually on step 3. May be need to use posix_kill instead of proc_terminate ?

[Ekstazi]

https://stackoverflow.com/questions/34926587/signal-being-forwarded-to-children-for-the-symfony-process-component

As i understand i cannot prevent SIGINT sent to process group. But problem with sending signal to children process from code still exist

[trowski]

Fix sending signals to the child process in d51bd9a48714c2efab9581b3bf2668e352806f67 using posix_kill instead of proc_terminate as you suggested, since the latter was sending the signal to the wrapper child instead of the target child. Obviously the Process::signal() method is not commonly used since this wasn't caught sooner. Generally child signal handlers catch signals from the console which are forwarded to all children. As you discovered, there is no way to change that behavior unless you change the group ID of the child process.

[Ekstazi]

Thx. I use Process::signal in my code.