<?php

$spec = array(
  0 => array('pipe', 'r'),
  1 => array('pipe', 'w'),
  2 => array('pipe', 'w'),
);

$pipes = array();
$proc = proc_open('sleep 30', $spec, $pipes);
list($stdin, $stdout, $stderr) = $pipes;

$read = array($stdout, $stderr);
$write = array();
$except = array();

$select_start = microtime(true);
stream_select($read, $write, $except, 0.999321, 80000);
$select_end = microtime(true);

printf(
  "select() took %d us to return.\n",
  ($select_end - $select_start) * 1000000);