parent start, pid 1807 1807 2013-01-14 15:20:05 parent continue child start, pid 1808 1808 2013-01-14 15:20:06 1808 2013-01-14 15:20:07 1808 2013-01-14 15:20:08 1808 2013-01-14 15:20:09 1808 2013-01-14 15:20:10 1807 2013-01-14 15:20:11 1807 2013-01-14 15:20:12 parent continue child start, pid 1809 1809 2013-01-14 15:20:13 1809 2013-01-14 15:20:14 1809 2013-01-14 15:20:15 1809 2013-01-14 15:20:16 1809 2013-01-14 15:20:17 1807 2013-01-14 15:20:18 1807 2013-01-14 15:20:19 child start, pid 1810 1810 2013-01-14 15:20:20 parent continue 1810 2013-01-14 15:20:21 1810 2013-01-14 15:20:22 1810 2013-01-14 15:20:23 1810 2013-01-14 15:20:24 1807 2013-01-14 15:20:25 1807 2013-01-14 15:20:26
父进程在pcntl_wait()将自己阻塞，等待子进程运行完了才接着运行。
3. 非阻塞方式
阻塞方式失去了多进程的并行性。还有一种方法，既可以回收已经结束的子进程，又可以并行。这就是非阻塞的方式。
修改脚本：
<?php // example of multiple processes date_default_timezone_set( 'Asia/Chongqing'); declare (ticks = 1); pcntl_signal(SIGCHLD, "garbage" ); echo "parent start, pid ", getmypid(), "\n" ; beep(); for ($i=0; $i<3; ++$i){ $pid = pcntl_fork(); if ($pid == -1){ die ("cannot fork" ); } else if ($pid > 0){ echo "parent continue \n"; for ($k=0; $k<2; ++$k){ beep(); } } else if ($pid == 0){ echo "child start, pid ", getmypid(), "\n" ; for ($j=0; $j<5; ++$j){ beep(); } exit (0); } } // parent while (1){ // do something else sleep(5); } // *** function garbage($signal){ echo "signel $signal received\n" ; while (($pid = pcntl_waitpid(-1, $status, WNOHANG))> 0){ echo "\t child end pid $pid , status $status\n" ; } } function beep(){ echo getmypid(), "\t" , date( 'Y-m-d H:i:s', time()), "\n" ; sleep(1); } ?>
用命令行运行
#php -f test.php &
输出结果
parent start, pid 2066 2066 2013-01-14 16:45:34 parent continue 2066 2013-01-14 16:45:35 child start, pid 2067 2067 2013-01-14 16:45:35 20662067 2013-01-14 16:45:362013-01-14 16:45:36 2067 2013-01-14 16:45:37 parent continue 2066 2013-01-14 16:45:37 child start, pid 2068 2068 2013-01-14 16:45:37 2067 2013-01-14 16:45:38 2068 2013-01-14 16:45:38 2066 2013-01-14 16:45:38 parent continue 2066 2013-01-14 16:45:40 child start, pid 2069 2069 2067 2013-01-14 16:45:40 2013-01-14 16:45:40 2068 2013-01-14 16:45:40 2066 2013-01-14 16:45:41 2069 2013-01-14 16:45:41 2068 2013-01-14 16:45:41 signel 17 received child end pid 2067, status 0 2069 2013-01-14 16:45:42 2068 2013-01-14 16:45:42 2069 2013-01-14 16:45:43 signel 17 received child end pid 2068, status 0 2069 2013-01-14 16:45:44 signel 17 received child end pid 2069, status 0
多个进程又并行运行了，而且运行大约10秒钟之后，用 ps -ef | grep php 查看正在运行的进程，只有一个进程
lqling 2066 1388 0 16:45 pts/1 00:00:00 php -f t5.php
是父进程，子进程被回收了。
子进程退出状态
pcntl_waitpid(-1, $status, WNOHANG) $status
返回子进程的结束状态
windows下多线程
windows系统不支持pcntl函数，幸好有curl_multi_exec()这个工具，利用内部的多线程，访问多个链接，每个链接可以作为一个任务。
编写脚本 test1.php
<?php date_default_timezone_set( 'Asia/Chongqing'); $tasks = array( 'http://localhost/feedbowl/t2.php?job=task1', 'http://localhost/feedbowl/t2.php?job=task2', 'http://localhost/feedbowl/t2.php?job=task3' ); $mh = curl_multi_init(); foreach ($tasks as $i => $task){ $ch[$i] = curl_init(); curl_setopt($ch[$i], CURLOPT_URL, $task); curl_setopt($ch[$i], CURLOPT_RETURNTRANSFER, 1); curl_multi_add_handle($mh, $ch[$i]); } do {$mrc = curl_multi_exec($mh,$active); } while ($mrc == CURLM_CALL_MULTI_PERFORM); while ($active && $mrc == CURLM_OK) { if (curl_multi_select($mh) != -1) { do {$mrc = curl_multi_exec($mh, $active); } while ($mrc == CURLM_CALL_MULTI_PERFORM); } } // completed, checkout result foreach ($tasks as $j => $task){ if (curl_error($ch[$j])){ echo "task ${j} [$task ] error " , curl_error($ch[$j]), "\r\n" ; } else { echo "task ${j} [$task ] get: \r\n" , curl_multi_getcontent($ch[$j]), "\r\n" ; } } ?>
编写脚本 test2.php
<?php date_default_timezone_set( 'Asia/Chongqing'); echo "child start, pid ", getmypid(), "\r\n" ; for ($i=0; $i<5; ++$i){ beep(); } exit (0); // *** function beep(){ echo getmypid(), "\t" , date('Y-m-d H:i:s' , time()), "\r\n"; sleep(1); } ?>
用命令行运行
#php -f test1.php &
输出结果