php curl CURLOPT_TIMEOUT_MS 小于1秒 解决方案

php的curl函数有多个参数:

 

CURLOPT_TIMEOUT_MS 设置cURL允许执行的最长毫秒数。  在cURL 7.16.2中被加入。从PHP 5.2.3起可使用。 所以使用的时候请先查看libcurl版本 curl --version

 

但是这个函数有个bug，如果时间小于1000毫秒也就是1秒的话，会立马报错，查看下面说明

 

　　If you want cURL to timeout in less than one second, you can use CURLOPT_TIMEOUT_MS, although there is a bug/"feature"  on "Unix-like systems" that causes libcurl to timeout immediately if the value is < 1000 ms with the error "cURL Error (28): Timeout was reached".  The explanation for this behavior is:
　　"If libcurl is built to use the standard system name resolver, that portion of the transfer will still use full-second resolution for timeouts with a minimum timeout allowed of one second."
　　What this means to PHP developers is "You can use this function without testing it first, because you can't tell if libcurl is using the standard system name resolver (but you can be pretty sure it is)"
　　The problem is that on (Li|U)nix, when libcurl uses the standard name resolver, a SIGALRM is raised during name resolution which libcurl thinks is the timeout alarm.
　　The solution is to disable signals using CURLOPT_NOSIGNAL.  Here's an example script that requests itself causing a 10-second delay so you can test timeouts:

　　

<?php
if (!isset($_GET['foo'])) {
        // Client
        $ch = curl_init('http://localhost/test/test_timeout.php?foo=bar');
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($ch, CURLOPT_NOSIGNAL, 1);
        curl_setopt($ch, CURLOPT_TIMEOUT_MS, 200);
        $data = curl_exec($ch);
        $curl_errno = curl_errno($ch);
        $curl_error = curl_error($ch);
        curl_close($ch);

        if ($curl_errno > 0) {
                echo "cURL Error ($curl_errno): $curl_error\n";
        } else {
                echo "Data received: $data\n";
        }
} else {
        // Server
        sleep(10);
        echo "Done.";
}
?> 

对，增加 curl_setopt($ch, CURLOPT_NOSIGNAL, 1)