PHP中的并行处理（简）

针对多核的cpu泛滥的今天，如何使用好这些CPU资源成了重要的话题。于是异步和并行便开始了大行其道。在PHP中也有异步或并行编程的概念。接下来让我们看具体的例子。

并行处理                                                                              

现在我们需要跑两个任务，分别为job1.php和job2.php

job1.php的代码如下：

$jobname = 'job1';
set_time_limit(0);
$secs = 30;

while ($secs) {
        echo 'current job is'.$jobname,'::',$secs,"\n";
        flush(); @ob_flush();  ## make sure that all output is sent in real-time
        $secs -= 1;
        $t = time();
        sleep(1); // pause
}

job2.php的代码只是在$jobname处为job2，其他和job1都一样。
有了任务，我们自然还需要执行的php文件，为run.php，代码如下：

#
# run.php
#
function JobStartAsync($server, $url, $port=80,$conn_timeout=30, $rw_timeout=86400)
{
    $errno = '';
    $errstr = '';
    
    set_time_limit(0);
    
    $fp = fsockopen($server, $port, $errno, $errstr, $conn_timeout);
    if (!$fp) {
       echo "$errstr ($errno)<br />\n";
       return false;
    }
    $out = "GET $url HTTP/1.1\r\n";
    $out .= "Host: $server\r\n";
    $out .= "Connection: Close\r\n\r\n";
    
    stream_set_blocking($fp, false);
    stream_set_timeout($fp, $rw_timeout);
    fwrite($fp, $out);
    
    return $fp;
}

// returns false if HTTP disconnect (EOF), or a string (could be empty string) if still connected
function JobPollAsync(&$fp) 
{
    if ($fp === false) return false;
    
    if (feof($fp)) {
        fclose($fp);
        $fp = false;
        return false;
    }
    
    return fread($fp, 10000);
}

###########################################################################################

 
if (1) {  /* SAMPLE USAGE BELOW */

    $fp1 = JobStartAsync('localhost','/jobs/job1.php');
    $fp2 = JobStartAsync('localhost','/jobs/job2.php');
    
    
    while (true) {
        sleep(1);
        
        $r1 = JobPollAsync($fp1);
        $r2 = JobPollAsync($fp2);
        
        if ($r1 === false && $r2 === false) break;
        
        echo "<b>r1 = </b>$r1<br>";
        echo "<b>r2 = </b>$r2<hr>";
        flush(); @ob_flush();
    }
    
    echo "<h3>Jobs Complete</h3>";
}

 就此完成，输出如下

r1 = HTTP/1.1 200 OK
Date: Wed, 03 Sep 2008 07:20:20 GMT
Server: Apache/2.2.4 (Unix) mod_ssl/2.2.4 OpenSSL/0.9.8d
X-Powered-By: Zend Core/2.5.0 PHP/5.2.5
Connection: close
Transfer-Encoding: chunked
Content-Type: text/html

7 current job is job1::30

r2 = HTTP/1.1 200 OK
Date: Wed, 03 Sep 2008 07:20:20 GMT
Server: Apache/2.2.4 (Unix) mod_ssl/2.2.4 OpenSSL/0.9.8d
X-Powered-By: Zend Core/2.5.0 PHP/5.2.5
Connection: close
Transfer-Encoding: chunked
Content-Type: text/html

7 current job is job2::30
----
r1 = 7 current job is  job1::29

r2 = 7 current job is  job2::29
----
r1 = 7 current job is  job1::28

r2 = 7 current job is  job2::28

----

 此处采用了fsockopen进行了实现，但是有时候，为了更高效，我们可以使用popen完成相同的功能。只是传入的command需要时运行php的command，比如php /xxx/xxx/xxx/job/job1.php (这对linux的情况)