PHP多线程的实现方法详解

多线程是java中一个很不错的东西,很多朋友说在php中不可以使用PHP多线程了,其实那是错误的说法PHP多线程实现方法和fsockopen函数有关,下面我们来介绍具体实现程序代码,有需要了解的同学可参考.

当有人想要实现并发功能时,他们通常会想到用fork或者spawn threads,但是当他们发现php不支持多线程的时候,大概会转换思路去用一些不够好的语言,比如perl.

其实的是大多数情况下,你大可不必使用 fork 或者线程,并且你会得到比用 fork 或 thread 更好的性能.

假设你要建立一个服务来检查正在运行的n台服务器,以确定他们还在正常运转,你可能会写下面这样的代码:

<?php
$hosts = array(
    "host1.sample.com",
    "host2.sample.com",
    "host3.sample.com"
);
$timeout = 15;
$status = array();
foreach ($hosts as $host) {
    $errno = 0;
    $errstr = "";
    $s = fsockopen($host, 80, $errno, $errstr, $timeout);
    if ($s) {
        $status[$host] = "Connected\n";
        fwrite($s, "HEAD / HTTP/1.0\r\nHost: $host\r\n\r\n");
        do {
            $data = fread($s, 8192);
            if (strlen($data) == 0) {
                break;
            }
            $status[$host].= $data;
        } while (true);
        fclose($s);
    } else {
        $status[$host] = "Connection failed: $errno $errst\r\n";
    }
}
print_r($status);
?>

它运行的很好,但是在fsockopen()分析完hostname并且建立一个成功的连接,或者延时$timeout秒之前,扩充这段代码来管理大量服务器将耗费很长时间.

因此我们必须放弃这段代码,我们可以建立异步连接-不需要等待fsockopen返回连接状态。PHP仍然需要解析hostname,所以直接使用ip更加明智,不过将在打开一个连接之后立刻返回,继而我们就可以连接下一台服务器.

有两种方法可以实现,PHP5中可以使用新增的stream_socket_client()函数直接替换掉fsocketopen(),PHP5之前的版本,你需要自己动手,用sockets扩展解决问题.

下面是PHP5中的解决方法,代码如下:

<?php
$hosts = array(
    "host1.sample.com",
    "host2.sample.com",
    "host3.sample.com"
);
$timeout = 15;
$status = array();
$sockets = array();
/* Initiate connections to all the hosts simultaneously */
foreach ($hosts as $id => $host) {
    $s = stream_socket_client(" 
$ 
$host:80", $errno, $errstr, $timeout, STREAM_CLIENT_ASYNC_CONNECT | STREAM_CLIENT_CONNECT);
    if ($s) {
        $sockets[$id] = $s;
        $status[$id] = "in progress";
    } else {
        $status[$id] = "failed, $errno $errstr";
    }
}
/* Now, wait for the results to come back in */
while (count($sockets)) {
    $read = $write = $sockets;
    /* This is the magic function - explained below */
    $n = stream_select($read, $write, $e = null, $timeout);
    if ($n > 0) {
        /* readable sockets either have data for us, or are failed
         * connection attempts */
        foreach ($read as $r) {
            $id = array_search($r, $sockets);
            $data = fread($r, 8192);
            if (strlen($data) == 0) {
                if ($status[$id] == "in progress") {
                    $status[$id] = "failed to connect";
                }
                fclose($r);
                unset($sockets[$id]);
            } else {
                $status[$id].= $data;
            }
        }
        /* writeable sockets can accept an HTTP request */
        foreach ($write as $w) {
            $id = array_search($w, $sockets);
            fwrite($w, "HEAD / HTTP/1.0\r\nHost: " . $hosts[$id] . "\r\n\r\n");
            $status[$id] = "waiting for response";
        }
    } else {
        /* timed out waiting; assume that all hosts associated
         * with $sockets are faulty */
        foreach ($sockets as $id => $s) {
            $status[$id] = "timed out " . $status[$id];
        }
        break;
    }
}
foreach ($hosts as $id => $host) {
    echo "Host: $host\n";
    echo "Status: " . $status[$id] . "\n\n";
}
?>

我们用stream_select()等待sockets打开的连接事件,stream_select()调用系统的select(2)函数来工作,前面三个参数是你要使用的streams的数组,你可以对其读取,写入和获取异常,分别针对三个参数,stream_select()可以通过设置$timeout（秒）参数来等待事件发生-事件发生时,相应的sockets数据将写入你传入的参数.

下面是PHP4.1.0之后版本的实现,如果你已经在编译PHP时包含了sockets(ext/sockets)支持，你可以使用根上面类似的代码,只是需要将上面的streams/filesystem函数的功能用ext/sockets函数实现,主要的不同在于我们用下面的函数代替stream_socket_client()来建立连接,代码如下:

<?php
// This value is correct for Linux, other systems have other values
define(&#39;EINPROGRESS&#39;, 115);
function non_blocking_connect($host, $port, &$errno, &$errstr, $timeout) {
    $ip = gethostbyname($host);
    $s = socket_create(AF_INET, SOCK_STREAM, 0);
    if (socket_set_nonblock($s)) {
        $r = @socket_connect($s, $ip, $port);
        if ($r || socket_last_error() == EINPROGRESS) {
            $errno = EINPROGRESS;
            return $s;
        }
    }
    $errno = socket_last_error($s);
    $errstr = socket_strerror($errno);
    socket_close($s);
    return false;
}
?>

现在用socket_select()替换掉stream_select(),用socket_read()替换掉fread(),用socket_write()替换掉fwrite(),用socket_close()替换掉fclose()就可以执行脚本了.

PHP5的先进之处在于,你可以用stream_select()处理几乎所有的stream-例如你可以通过include STDIN用它接收键盘输入并保存进数组,你还可以接收通过proc_open()打开的管道中的数据.

下面来分享一个PHP多线程类,代码如下:

<?php
/*
 * @title:      PHP多线程类(Thread)
 * @version:    1.0
 * @author:     phper.org.cn < web@phper.org.cn >
 * @published:  2010-11-2
 *
 * PHP多线程应用示例：
 *  require_once &#39;thread.class.php&#39;;
 *  $thread = new thread();
 *  $thread->addthread(&#39;action_log&#39;,&#39;a&#39;);
 *  $thread->addthread(&#39;action_log&#39;,&#39;b&#39;);
 *  $thread->addthread(&#39;action_log&#39;,&#39;c&#39;);
 *  $thread->runthread();
 *
 *  function action_log($info) {
 *      $log = &#39;log/&#39; . microtime() . &#39;.log&#39;;
 *      $txt = $info . "\r\n\r\n" . &#39;Set in &#39; . Date(&#39;h:i:s&#39;, time()) . (double)microtime() . "\r\n";
 *      $fp = fopen($log, &#39;w&#39;);
 *      fwrite($fp, $txt);
 *      fclose($fp);
 *  }
*/
lassthread {
    var $hooks = array();
    var $args = array();
    function thread() {
    }
    function addthread($func) {
        $args = array_slice(func_get_args() , 1);
        $this->hooks[] = $func;
        $this->args[] = $args;
        return true;
    }
    function runthread() {
        if (isset($_GET[&#39;flag&#39;])) {
            $flag = intval($_GET[&#39;flag&#39;]);
        }
        if ($flag || $flag === 0) {
            call_user_func_array($this->hooks[$flag], $this->args[$flag]);
        } else {
            for ($i = 0, $size = count($this->hooks); $i < $size; $i++) {
                $fp = fsockopen($_SERVER[&#39;HTTP_HOST&#39;], $_SERVER[&#39;SERVER_PORT&#39;]); //开源代码phprm.com
                if ($fp) {
                    $out = "GET {$_SERVER[&#39;PHP_SELF&#39;]}?flag=$i HTTP/1.1\r\n";
                    $out.= "Host: {$_SERVER[&#39;HTTP_HOST&#39;]}\r\n";
                    $out.= "Connection: Close\r\n\r\n";
                    fputs($fp, $out);
                    fclose($fp);
                }
            }
        }
    }
?>