note 102765 modified in function.pcntl-signal by danbrown

I was having some issues with processing a signal using an object method I use for something else as well. In particular, I wanted to handle SIGCHLD with my own method "do_reap()" which I also call after a stream_select timeout and that uses a non-blocking pcntl_waitpid function.

The method was called when the signal was received but it couldn't reap the child.

The only way it worked was by creating a new handler that itself called do_reap().

So in other words, the following does not work:

<?php
class Parent {
  /* ... */
  private function do_reap(){
    $p = pcntl_waitpid(-1,$status,WNOHANG);
    if($p > 0){
      echo "\nReaped zombie child " . $p;
    }

   public function run(){
    /* ... */
    pcntl_signal(SIGCHLD,array(&$this,"do_reap"));
    $readable = @stream_select($read,$null,$null,5); // 5 sec timeout
    if($readable === 0){
      // we got a timeout
      $this->do_reap();
   }
}
?>

But this work:

<?php
class Parent {
  /* ... */
  private function do_reap(){
    $p = pcntl_waitpid(-1,$status,WNOHANG);
    if($p > 0){
      echo "\nReaped zombie child " . $p;
    }

   public function run(){
    /* ... */
    pcntl_signal(SIGCHLD,array(&$this,"child_died"));
    $readable = @stream_select($read,$null,$null,5); // 5 sec timeout
    if($readable === 0){
      // we got a timeout
      $this->do_reap();
   }

    private function child_died(){
      $this->do_reap();
    }
}
?>

--was--
I was having some issues with processing a signal using an object method I use for something else as well. In particular, I wanted to handle SIGCHLD with my own method "do_reap()" which I also call after a stream_select timeout and that uses a non-blocking pcntl_waitpid function.

The method was called when the signal was received but it couldn't reap the child.

The only way it worked was by creating a new handler that itself called do_reap().

So in other words, the following does not work:
class Parent {
  /* ... */
  private function do_reap(){
    $p = pcntl_waitpid(-1,$status,WNOHANG);
    if($p > 0){
      echo "\nReaped zombie child " . $p;
    }

   public function run(){
    /* ... */
    pcntl_signal(SIGCHLD,array(&$this,"do_reap"));
    $readable = @stream_select($read,$null,$null,5); // 5 sec timeout
    if($readable === 0){
      // we got a timeout
      $this->do_reap();
   }
}

But this work:

class Parent {
  /* ... */
  private function do_reap(){
    $p = pcntl_waitpid(-1,$status,WNOHANG);
    if($p > 0){
      echo "\nReaped zombie child " . $p;
    }

   public function run(){
    /* ... */
    pcntl_signal(SIGCHLD,array(&$this,"child_died"));
    $readable = @stream_select($read,$null,$null,5); // 5 sec timeout
    if($readable === 0){
      // we got a timeout
      $this->do_reap();
   }

    private function child_died(){
      $this->do_reap();
    }
}

http://php.net/manual/en/function.pcntl-signal.php