Bug #68530 memory leak with innodb memcached plugin for stale connection

• Submitted: 28 Feb 2013 21:32
• Modified: 22 Aug 2013 15:44
• Reporter: Jijo Varghese
• Status: Closed
• Category: MySQL Server: Memcached
• Severity: S1 (Critical)
• Version: 5.6.10 GA
• OS: Linux (Centos 5)
• CPU Architecture: Any
• Tags: memcached plugin, memory leak

[28 Feb 2013 21:32] Jijo Varghese

Description:
innodb memcached plugin leaks memory on every connection

How to repeat:
very easy to reproduce.  just use any app or script that uses new connection - memslap does NOT meet this so we'll use https://github.com/antirez/mc-benchmark

Install mysql and memcached plugin as documented  
rpm -Uvh MySQL-server-5.6.10-1.rhel5.x86_64.rpm
mysql> source /usr/share/mysql/innodb_memcached_config.sql;
mysql> install plugin daemon_memcached soname "libmemcached.so";

Compile and install https://github.com/antirez/mc-benchmark/archive/master.zip
In one window
# echo 1 > /proc/sys/net/ipv4/tcp_tw_reuse
# ./mc-benchmark  -k 0 -l -c 400 -q

In another
# top -b -d 5 | grep -w mysqld
22284 mysql     18   0 1204m 673m 7060 S  4.0  4.4   6:28.23 mysqld
22284 mysql     18   0 1204m 675m 7060 S 13.2  4.4   6:28.89 mysqld
22284 mysql     18   0 1205m 676m 7060 S 19.4  4.4   6:29.86 mysqld
22284 mysql     18   0 1205m 677m 7060 S  8.4  4.4   6:30.28 mysqld
22284 mysql     18   0 1206m 679m 7060 S 24.2  4.4   6:31.49 mysqld
22284 mysql     18   0 1206m 680m 7060 S  8.2  4.4   6:31.90 mysqld
22284 mysql     18   0 1207m 682m 7060 S 25.6  4.4   6:33.18 mysqld
22284 mysql     18   0 1207m 684m 7060 S  9.8  4.5   6:33.67 mysqld

[17 Apr 2013 10:19] yang ting

I also met! 
 6836 my4444    18   0 39.4g  22g 7040 S 300.2 23.8   4:50.36 mysqld                                                     
 6836 my4444    18   0 39.7g  22g 7040 S 294.9 23.9   4:53.33 mysqld                                                     
 6836 my4444    18   0 40.0g  22g 7040 S 299.9 24.0   4:56.35 mysqld                                                     
 6836 my4444    18   0 40.4g  22g 7040 S 306.6 24.1   4:59.44 mysqld                                                     
 6836 my4444    18   0 40.7g  22g 7040 S 296.9 24.2   5:02.43 mysqld                                                     
 6836 my4444    18   0 41.1g  22g 7040 S 289.6 24.3   5:05.34 mysqld                                                     
 6836 my4444    18   0 41.4g  22g 7040 S 293.7 24.4   5:08.30 mysqld                                                     
 6836 my4444    18   0 41.7g  23g 7040 S 306.5 24.5   5:11.38 mysqld                                                     
 6836 my4444    18   0 42.0g  23g 7040 S 294.6 24.6   5:14.35 mysqld                                                     
 6836 my4444    18   0 42.3g  23g 7040 S 297.5 24.7   5:17.34 mysqld                                                     
 6836 my4444    18   0 42.7g  23g 7040 S 292.1 24.7   5:20.29 mysqld                                                     
 6836 my4444    18   0 43.0g  23g 7040 S 281.3 24.8   5:23.12 mysqld

[22 Aug 2013 15:44] Bugs System

Noted in 5.6.13, 5.7.2 changelog.

"Stale InnoDB memcached connections would result in a memory leak."

Thank you for the bug report.