优化curl并发使用

经典curl并发的处理流程：首先将所有的URL压入并发队列, 然后执行并发过程, 等待所有请求接收完之后进行数据的解析等后续处理。

在实际的处理过程中, 受网络传输的影响, 部分URL的内容会优先于其他URL返回, 但是经典curl并发必须等待最慢的那个URL返回之后才开始处理, 等待也就意味着CPU的空闲和浪费. 如果URL队列很短, 这种空闲和浪费还处在可接受的范围, 但如果队列很长, 这种等待和浪费将变得不可接受.

优化的方式时当某个URL请求完毕之后尽可能快的去处理它, 边处理边等待其他的URL返回, 而不是等待那个最慢的接口返回之后才开始处理等工作, 从而避免CPU的空闲和浪费. 下面贴上具体的实现:

function multiCurl($url, $log) {
	    $queue = curl_multi_init();

	    foreach($log as $info) {
                $ch = curl_init();
	        curl_setopt($ch, CURLOPT_URL, $url);
	        curl_setopt($ch, CURLOPT_POST, 1);
		curl_setopt($ch, CURLOPT_TIMEOUT, 3);
		curl_setopt($ch, CURLOPT_POSTFIELDS, $info);
	        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	        curl_setopt($ch, CURLOPT_HEADER, 0);
	        curl_setopt($ch, CURLOPT_NOSIGNAL, true);
	        curl_multi_add_handle($queue, $ch);
	    }

	    $responses = array();
	    do {
	        while (($code = curl_multi_exec($queue, $active)) == CURLM_CALL_MULTI_PERFORM) ;

	        if ($code != CURLM_OK) { break; }

	        // a request was just completed -- find out which one
	        while ($done = curl_multi_info_read($queue)) {

	            // get the info and content returned on the request
	            //$info = curl_getinfo($done['handle']);
	            //$error = curl_error($done['handle']);
	            $results = curl_multi_getcontent($done['handle']);
	            //$responses[] = compact('info', 'error', 'results');
	            $responses[] = $results;

	            // remove the curl handle that just completed
	            curl_multi_remove_handle($queue, $done['handle']);
	            curl_close($done['handle']);
	        }

	        // Block for data in / output; error handling is done by curl_multi_exec
	        if ($active > 0) {
	            curl_multi_select($queue, 0.5);
	        }

	    } while ($active);

	    curl_multi_close($queue);
	    return json_encode($responses);
}

转自:http://www.j135.com/?p=684