PHP编程：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 = '';
$content = file_get_contents($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 */
?>