exec() with timeout

Question

I'm looking for a way to run a PHP process with a timeout. Currently I'm simply using exec(), but it does not provide a timeout option.

What I also tried is opening the process using proc_open() and using stream_set_timeout() on the resulting pipe, but that didn't work either.

So, is there any way to run a command (a PHP command to be precise) with a timeout? (PS: This is for cases where the max_execution_time limit fails, so no need to suggest that.)

(By the way, I also need to retrieve the return code of the process.)

Answer 1

The timeout {$time} command solution does not work properly when it's called from a PHP script. In my case, with a ssh command to a wrong server (rsa key not found, and the server ask for a password), the process still alive after the defined timeout.

However I've found a function that works fine here:

http://blog.dubbelboer.com/2012/08/24/execute-with-timeout.html

C&P:

/**
 * Execute a command and return it's output. Either wait until the command exits or the timeout has expired.
 *
 * @param string $cmd     Command to execute.
 * @param number $timeout Timeout in seconds.
 * @return string Output of the command.
 * @throws \Exception
 */
function exec_timeout($cmd, $timeout) {
  // File descriptors passed to the process.
  $descriptors = array(
    0 => array('pipe', 'r'),  // stdin
    1 => array('pipe', 'w'),  // stdout
    2 => array('pipe', 'w')   // stderr
  );

  // Start the process.
  $process = proc_open('exec ' . $cmd, $descriptors, $pipes);

  if (!is_resource($process)) {
    throw new \Exception('Could not execute process');
  }

  // Set the stdout stream to none-blocking.
  stream_set_blocking($pipes[1], 0);

  // Turn the timeout into microseconds.
  $timeout = $timeout * 1000000;

  // Output buffer.
  $buffer = '';

  // While we have time to wait.
  while ($timeout > 0) {
    $start = microtime(true);

    // Wait until we have output or the timer expired.
    $read  = array($pipes[1]);
    $other = array();
    stream_select($read, $other, $other, 0, $timeout);

    // Get the status of the process.
    // Do this before we read from the stream,
    // this way we can't lose the last bit of output if the process dies between these     functions.
    $status = proc_get_status($process);

    // Read the contents from the buffer.
    // This function will always return immediately as the stream is none-blocking.
    $buffer .= stream_get_contents($pipes[1]);

    if (!$status['running']) {
      // Break from this loop if the process exited before the timeout.
      break;
    }

    // Subtract the number of microseconds that we waited.
    $timeout -= (microtime(true) - $start) * 1000000;
  }

  // Check if there were any errors.
  $errors = stream_get_contents($pipes[2]);

  if (!empty($errors)) {
    throw new \Exception($errors);
  }

  // Kill the process in case the timeout expired and it's still running.
  // If the process already exited this won't do anything.
  proc_terminate($process, 9);

  // Close all streams.
  fclose($pipes[0]);
  fclose($pipes[1]);
  fclose($pipes[2]);

  proc_close($process);

  return $buffer;
}

Answer 2

Improving on other solutions I came up with this:

function exec_timeout($cmd,$timeout=60){
        $start=time();
        $outfile=uniqid('/tmp/out',1);
        $pid=trim(shell_exec("$cmd >$outfile 2>&1 & echo $!"));
        if(empty($pid)) return false;
        while(1){
                if(time()-$start>$timeout){
                        exec("kill -9 $pid",$null);
                        break;
                }
                $exists=trim(shell_exec("ps -p $pid -o pid="));
                if(empty($exists)) break;
                sleep(1);
        }
        $output=file_get_contents($outfile);
        unlink($outfile);
        return $output;
}