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Bug #71989 Unable to call the exec function asynchronously
Submitted: 2016-04-08 12:59 UTC Modified: 2016-06-23 18:15 UTC
From: ivan dot shib at gmail dot com Assigned:
Status: Not a bug Package: Output Control
PHP Version: 7.0.5 OS: 4.1.19-boot2docker x86_64 Linux
Private report: No CVE-ID: None
 [2016-04-08 12:59 UTC] ivan dot shib at gmail dot com
In the php code run the following command:

exec('php -f '.escapeshellarg(ROOT_DIR.'/index.php').' > /dev/null 2>&1 &');

Got the following record in the logs:
2016-04-08T12:55:38.201816261Z [08-Apr-2016 12:55:38] ALERT: oops, unknown child (16) exited with code 0. Please open a bug report (

If we remove ' > /dev/null 2>&1 &' part from code then it works fine but not asynchronously.

Please note that in PHP v 7.0.3 the code above worked fine.


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 [2016-06-23 18:15 UTC]
-Status: Open +Status: Not a bug
 [2016-06-23 18:15 UTC]
This is not an error. You are a creating a child process inside the shell without correctly handling it using waitpid. Therefore the FPM module finds an unknown child and writes this warning. The correct way to do this is using something along the line of:

$p = pcntl_fork();
if ($p == 0) {
  // child process
  exec('php -f index.php');
} else if ($p > 0) {
  // parent
  waitpid($p, $status);
} else {
  // error
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