php simultaneous file downloads from the same browser and same php script

Question

<?php

$filename= './get/me/me_'.rand(1,100).'.zip';

header("Content-Length: " . filesize($filename));
header('Content-Type: application/zip');
header('Content-Disposition: attachment; filename=foo.zip');

readfile($filename);
?>

Hi, I have this simple code that forces a random file download, my problem is that if I call the script two or more times from the same browser the second download won't start until the first is completed or interrupted. Thus I can download only one file per time. Do you have any clue?

Answer 1

This may be related to PHP's session handling.

Using the default session handler, when a PHP script opens a session it locks it. Subsequent scripts that need to access it have to wait until the first script is finished with it and unlocks it (which happens automatically at shutdown, or by session_write_close() ). This will manifest as the script not doing anything till the previous one finishes in exactly the same way you describe.

Clearly you aren't starting the session explicitly, but there's a config flag that causes the session to start automatically: session.auto_start - http://www.php.net/manual/en/session.configuration.php

Either use phpinfo() to determine if this is set to true, or look in your config. You could also try adding session_write_close() to the top of the script, see if it makes the issue go away.