/ p>

  $ i = 0; 
 while（$ row = $ result-> fetch_object（））{
 $ data = curl_multi_getcontent（$ ch [$ i]）; 
 $ json_data = json_decode（$ data）; 
 var_dump（$ json_data）; 
 

您是否忘记增加$ i？如果是这样，你已经抓住了$ ch [0]的内容，然后再次调用curl_multi_getcontent。

此外，我写了一篇博文=http://adamjonrichardson.com/2013/09/23/making-concurrent-curl-requests-using-phps-curl_multi-functions/ =nofollow>使用PHP的cURL扩展的并发请求，并且它包含curl多请求的一般函数。您可以按以下方式调用此函数：

  $ responses = multi（[
 $ requests = [
 ['url'=>'https://mysite.com/search/username1/']，
 ['url'=>'https://mysite.com/search/username2/' ]，
 ['url'=>'https://mysite.com/search/username3/'] 
] 
 $ opts = [
 CURLOPT_CAINFO => cacert.pem'，
 CURLOPT_USERPWD =>username：password
] 
]）;然后，你循环通过响应数组： 






 $ b 
  foreach（$ responses as $ response）{
 if（$ response ['error'] {
 // handle error 
 continue; 
} 
 //检查空响应
 if（$ response ['data'] === null）{
 //检查$ response ['info'] 
 continue; 
} 
 //处理数据
 $ data = json_decode（$ response ['data']）; 
 //做某事
} 

使用此功能，您可以使用以下调用进行访问https网站的简单测试：
  multi（
 $ requests = [
'google'=> ['url'=>'https： /www.google.com']，
'linkedin'=> ['url'=>'https://www.linkedin.com/'] 
]，
 $ opts = [
 CURLOPT_CAINFO =>'/path/to/your/cacert.pem'，
 CURLOPT_SSL_VERIFYPEER => true 
] 
）; 
 
 

I have been following this tutorial on how to use curl_multi. http://arguments.callee.info/2010/02/21/multiple-curl-requests-with-php/

I can't tell what I am doing wrong, but curl_multi_getcontent is returning null. It is suppose to return JSON. I know it is not the mysql call as I had it working with a while loop and standard curl_exec, but The page was taking too long to load. (I've changed some of the setopt details for security)

Relevant PHP Code snippet. I do close the while loop in the end. 
$i = 0;
$ch = array();
$mh = curl_multi_init();
while($row = $result->fetch_object()){
   $ch[$i] = curl_init();
   curl_setopt($ch[$i], CURLOPT_CAINFO, 'cacert.pem');
   curl_setopt($ch[$i], CURLOPT_USERPWD, "$username:$password");
   curl_setopt($ch[$i], CURLOPT_RETURNTRANSFER, true); 
   curl_setopt($ch[$i], CURLOPT_URL, 'https://mysite.com/search/'.$row->username.'/');
   curl_multi_add_handle($mh, $ch[$i]);
   $i++;
}
$running = 0;
do {
    curl_multi_exec($mh, $running);
} while ($running > 0);
$result->data_seek(0);
$i = 0;
while ($row = $result->fetch_object()) {
    $data = curl_multi_getcontent($ch[$i]);
    $json_data = json_decode($data);
    var_dump($json_data);

EDIT

Here is the code that currently works, but causes the page to load too slowly
$ch = curl_init();
curl_setopt($ch, CURLOPT_CAINFO, 'cacert.pem');
curl_setopt($ch, CURLOPT_USERPWD, "$username:$password");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
while($row = $result->fetch_object()){
   curl_setopt($ch, CURLOPT_URL, 'https://mysite.com/search/'.$row->username.'/');
   $data = curl_exec($ch);
   $json_data = json_decode($data);
   var_dump($json_data);
}




I'm wondering:
$i = 0;
while ($row = $result->fetch_object()) {
    $data = curl_multi_getcontent($ch[$i]);
    $json_data = json_decode($data);
    var_dump($json_data);

Are you forgetting to increment $i? If so, you already grabbed the content for $ch[0], and then you call curl_multi_getcontent again.

Also, I've written a blog post covering concurrent requests with PHP's cURL extension, and it contains a general function for curl multi requests. You could call this function in the following manner:
$responses = multi([
    $requests = [
        ['url' => 'https://mysite.com/search/username1/'],
        ['url' => 'https://mysite.com/search/username2/'],
        ['url' => 'https://mysite.com/search/username3/']
    ]
    $opts = [
        CURLOPT_CAINFO => 'cacert.pem',
        CURLOPT_USERPWD => "username:password"
    ]
]);

Then, you cycle through the responses array:
foreach ($responses as $response) {
    if ($response['error'] {
        // handle error
        continue;
    }
    // check for empty response
    if ($response['data'] === null) {
        // examine $response['info']
        continue;
    }
    // handle data
    $data = json_decode($response['data']);
    // do something
}

Using this function, you could make a simple test of accessing https sites using the following call:
multi(
    $requests = [
        'google' => ['url' => 'https://www.google.com'],
        'linkedin' => ['url'=> 'https://www.linkedin.com/']
    ],
    $opts = [
        CURLOPT_CAINFO => '/path/to/your/cacert.pem',
        CURLOPT_SSL_VERIFYPEER => true
    ]
);