Description:
------------
If you use multicurl simmilar to the sample mentioned here:

http://php.net/manual/en/function.curl-multi-init.php

your code will run forever or reach max_execution_time.

Test script:
---------------
<?php
// create both cURL resources
$ch1 = curl_init();
$ch2 = curl_init();

// set URL and other appropriate options
curl_setopt($ch1, CURLOPT_URL, "http://lxr.php.net/");
curl_setopt($ch1, CURLOPT_HEADER, 0);
curl_setopt($ch2, CURLOPT_URL, "http://www.php.net/");
curl_setopt($ch2, CURLOPT_HEADER, 0);

//create the multiple cURL handle
$mh = curl_multi_init();

//add the two handles
curl_multi_add_handle($mh,$ch1);
curl_multi_add_handle($mh,$ch2);

$active = null;
//execute the handles
do {
    $mrc = curl_multi_exec($mh, $active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);

while ($active && $mrc == CURLM_OK) {
    if (curl_multi_select($mh) != -1) {
        do {
            $mrc = curl_multi_exec($mh, $active);
        } while ($mrc == CURLM_CALL_MULTI_PERFORM);
    }
}

//close the handles
curl_multi_remove_handle($mh, $ch1);
curl_multi_remove_handle($mh, $ch2);
curl_multi_close($mh);


Expected result:
----------------
HTML of both URL's

Actual result:
--------------
Nothing happens.

strace output shows endless:

select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})
select(5, [], [4], [], {1, 0})          = 1 (out [4], left {0, 999999})