mysql_pconnect leaks file descriptors on reconnect

Bug #55473 mysql_pconnect leaks file descriptors on reconnect
Submitted: 2011-08-21 10:52 UTC Modified: 2011-08-22 10:57 UTC
From: littlesavage at rambler dot ru Assigned: andrey (profile)
Status: Closed Package: MySQL related
PHP Version: 5.3.7 OS:
Private report: No CVE-ID: None

 [2011-08-21 10:52 UTC] littlesavage at rambler dot ru

Description:
------------
Whem Mysql closes created by mysql_pconnect() peristent connection, file descriptor lefts opened and is never reused.
I have a server that stops working due to opened file descriptors limit.

Test script:
---------------
<?php

function connect($passwd) {
   $conn = mysql_pconnect('localhost:3306','root', $passwd);
   if (!$conn)
      die(mysql_error()."\n");
   mysql_query("set wait_timeout=5", $conn);
   return $conn;
}

$passwd = $argv[1];
$conn = connect($passwd);

for($i=0;$i<10;$i++) {
   /* wait while mysql closes connection */
   sleep(6);

   if (!mysql_ping($conn)) {
      echo "reconnect\n";
      $conn = connect($passwd);
   }

   $r = mysql_query('select 1', $conn);
   $error = $r ? 'OK' : mysql_error();
   $opened_files = trim(exec("lsof -np " . getmypid() . " | wc -l"));
   echo "$error. opened files: $opened_files\n";
}

?>


Expected result:
----------------
$ php ./test.php
reconnect
OK. opened files: 76
reconnect
OK. opened files: 76
reconnect
OK. opened files: 76
reconnect
OK. opened files: 76
...

Actual result:
--------------
$ php ./test.php
reconnect
OK. opened files: 76
reconnect
OK. opened files: 77
reconnect
OK. opened files: 78
reconnect
OK. opened files: 79
...

Patches

Bug55473.diff (last revision 2011-08-22 08:33 UTC by laruence@php.net)

Pull Requests

History

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 [2011-08-22 03:05 UTC] laruence@php.net

I can't reproduce this bug in PHP-5.3.7 on Linux Redhat(64-bit).
What's your OS type?

 [2011-08-22 06:20 UTC] littlesavage at rambler dot ru

I have found this bug on Debian squeeze (x86_64), php PHP 5.3.6-6~dotdeb.1 with Suhosin-Patch, mysql 5.1.58.
Then i repeat it on FreeBSD 9, php 5.3.7 with Suhosin-Patch, mysql 5.5.12.

On FreeBSD i have found that this bug reproducable only when i use mysqlnd native driver. Everything work as expected with standart mysql driver.

 [2011-08-22 08:35 UTC] laruence@php.net

I found this is due to, when doing a reconnect, mysqlnd_connect didn't free the 
stream. I have submitted a patch, but need georg&andrey&ulf to review first..

 [2011-08-22 09:01 UTC] laruence@php.net

and the reason for why this cleanup cound not be done in dtor,  is that in dtor, 
it also clean the content, option, which should not free at that memont,

and that is not a dtor time in theory.

 [2011-08-22 10:57 UTC] laruence@php.net

-Status: Analyzed +Status: Closed -Assigned To: +Assigned To: andrey

 [2012-02-28 06:46 UTC] jim at addmired dot com

We are still getting hit by this bug. This patch hasn't been applied in 5.3 
releases yet, apparently. It was supposed to go into 5.3.8 but still no joy. =( 
Any hope of this getting into the code now? =(