PHP使用pcntl_fork实现多进程下载图片的方法

# mkdir php 
# cd php 
# apt-get source php5 
# cd php5-(WHATEVER_RELEASE)/ext/pcntl 
# phpize 
# ./configure (注一) 
# make 
# make install phpize 命令是用来准备 PHP 外挂模块的编译环境的

void pcntl_exec(string $path [,array $args [,array $envs ]])

$cmds=array( 
        array('/home/jerry/projects/www/test2.php'), 
        array('/home/jerry/projects/www/test3.php') 
); 
 
foreach($cmds as $cmd){ 
        $pid=pcntl_fork(); 
        if($pid==-1){ 
        //进程创建失败 
            echo '创建子进程失败时返回-1'; 
            exit(-1); 
        } 
        else if($pid){ 
        //父进程会得到子进程号，所以这里是父进程执行的逻辑 
            pcntl_wait($status,WNOHANG); 
        } 
        else{ 
        //子进程处理逻辑 
            sleep(5); 
            pcntl_exec('/usr/bin/php',$cmd); 
            exit(0); 
        } 
}

#!/usr/bin/php 
<?php 
// 需要抓取的网页地址 
$url = 'http://www.php.cn'; 
$content = file_get_contents($url); 
preg_match_all('/<imgs+src="(.*?)"/', $content, $matches,PREG_SET_ORDER); 
echo "已发现".count($matches)."张图片n"; 
 
list($sm, $ss) = explode(" ", microtime()); 
foreach ($matches as $k => $val) 
{ 
 $pid[$k] = pcntl_fork(); 
 if(!$pid[$k]) 
 { 
  download($url, $val); 
  // 子进程要exit否则会进行递归多进程，父进程不要exit否则终止多进程 
  exit(0); 
 } 
 
 if ($pid[$k]) 
 { 
//    pcntl_waitpid($pid[$k], $status, WUNTRACED); 
 } 
 
} 
echo "下载完成n"; 
 
list($em, $es) = explode(" ", microtime()); 
 
echo "用时：",($es+$em) - ($ss + $sm),"n"; 
/** 
 * 抓取网页图片 
 *  
 */ 
function download($url, $val) 
{ 
 $pic_url = $val[1]; 
 if (strpos($val[1], '//') !== false) 
 { 
  ; 
 } 
 elseif (preg_match('@^(.*?)/@', $val[1], $inner_matches) == 0) 
 { 
  $pic_url = $url.$val[1]; 
 } 
 elseif (preg_match('@[:.]@', $inner_matches[1], $tmp_matches) == 0) 
 { 
  $pic_url = $url.$val[1]; 
 } 
 
 $pic = file_get_contents($pic_url); 
 
 if ($pic === false) 
 { 
  return; 
 } 
 
 preg_match('@/([^/]+)$@', $pic_url, $tmp_matches); 
 // 可使用assert处理异常 
 $pic_file_name = $tmp_matches[1]; 
 $f = fopen("tmp/".$pic_file_name, "wb"); # 
 fwrite($f, $pic); 
 fclose($f); 
} 
 
/* End of file pcntl_fork.php */ 
?>