Bug #8933 Memory leak when making a large number of connections
Submitted: 3 Mar 2005 22:25 Modified: 7 May 2005 15:07
Reporter: [ name withheld ] Email Updates:
Status: Can't repeat Impact on me:
Category:MySQL Server Severity:S3 (Non-critical)
Version:4.1.6-gamma-standard OS:Linux (Fedora Core 2 (2.6.9-1.6_FC2))
Assigned to: CPU Architecture:Any

[3 Mar 2005 22:25] [ name withheld ]
The process size of the mysql processes appears to grow slowly if applications rapidly connect and disconnect from the database.

In a long running server (90+ days), this problem eventually caused the mysql processes to become so large as to impact performance.  Restarting the mysql server resolves the issue, but that shouldn't be necessary.

How to repeat:
If you execute the following perl script and do 'ps aux | grep mysql' every 5-10 minutes on the database host, you can watch the size (RSS) of the mysql processes grow slowly.


use DBI;

my $i;
for ($i=0; $i<50000; $i++) {
    my $mysql_dbh =
                     "user", "the user's password",
                     {RaiseError => 1, AutoCommit => 1});


    print "$i...\n" if ($i % 100 == 0);

Suggested fix:
Run a version of mysql with a memory leak detector compiled in to see if the leak can be easily munched.
[12 Apr 2005 19:41] Bruno Dingfelder
I have an application in PHP that also requires a large number of connections,
and after a few days my server performance will drop fast. When I check the
mysql server process I also noticed it grows:

@ 12:51 Pm

RES = 6940, % MEM = 2.8

@ 12:58 Pm

RES = 7628, % MEM =  3.1

I am running Default Mysql Php Rpms in Fedora Core 2