# Mysql restarted automatically because of Out of memory **URL:** \ **Category:** Other MySQL® Questions\ **Created:** [June 20, 2012, 4:48am UTC](https://forums.percona.com/t/mysql-restarted-automatically-because-of-out-of-memory/1833 "2012-06-20T04:48:41Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![mchauhan75](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@mchauhan75](https://forums.percona.com/u/mchauhan75)\ **Post date:** [June 20, 2012, 4:48am UTC](https://forums.percona.com/t/mysql-restarted-automatically-because-of-out-of-memory/1833/1 "2012-06-20T04:48:41Z")
Hi All, We have Percona Mysql Server version: 5.5.16 with Master - Slave replication. Mysql on Master server got restarted automatically, we checked the Kernel and system logs and found that it was restarted because of Out of memory. After restart, top command shows that 97.3% memory is holding my Mysql even there is no query running. Total Memory is 32G Memory assigned to innodb buffer pool = 28G As The Linux kernel has a functionality called Out Of Memory Killer (or OOM Killer) responsible for dealing with memory exhaustion. If system reaches a point where it may soon run out of all memory, OOM Killer looks for a process it could kill and ends its life. Please suggest?? top output ################### top - 03:05:16 up 39 days, 16:56, 3 users, load average: 0.01, 0.05, 0.07 Tasks: 277 total, 1 running, 276 sleeping, 0 stopped, 0 zombie Cpu(s): 0.1%us, 0.0%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 32949816k total, 32613172k used, 336644k free, 83848k buffers Swap: 524280k total, 267588k used, 256692k free, 295836k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 21988 mysql 15 0 31.0g 30g 4540 S 1.7 97.3 362:58.01 mysqld 5318 root 15 0 12872 1260 832 R 0.7 0.0 0:00.02 top 23532 gsc 18 0 12872 1196 764 S 0.3 0.0 15:43.64 top 1 root 15 0 10348 84 52 S 0.0 0.0 4:32.92 init [root@avl-db10 logs]# free -m total used free shared buffers cached Mem: 32177 31850 326 0 84 289 -/+ buffers/cache: 31476 700 Swap: 511 261 250 Kernel Logs Node 1 HighMem per-cpu: empty Free pages: 85048kB (0kB HighMem) Active:6438386 inactive:1742978 dirty:0 writeback:0 unstable:0 free:21262 slab:7758 mapped-file:984 mapped-anon:7948245 pagetables:16991 Node 0 DMA free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages\_scanned:0 all\_unreclaimable? no lowmem\_reserve: 0 0 16160 16160 Node 0 DMA32 free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages\_scanned:0 all\_unreclaimable? no lowmem\_reserve: 0 0 16160 16160 Node 0 Normal free:11436kB min:11508kB low:14384kB high:17260kB active:11474648kB inactive:4991256kB present:16547840kB pages\_scanned:28277512 all\_unreclaimable? yes lowmem\_reserve: 0 0 0 0 Node 0 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages\_scanned:0 all\_unreclaimable? no lowmem\_reserve: 0 0 0 0 Node 1 DMA free:10772kB min:4kB low:4kB high:4kB active:0kB inactive:0kB present:10388kB pages\_scanned:0 all\_unreclaimable? yes lowmem\_reserve: 0 3243 16121 16121 Node 1 DMA32 free:53808kB min:2308kB low:2884kB high:3460kB active:1540788kB inactive:1656616kB present:3321540kB pages\_scanned:13029052 all\_unreclaimable? yes lowmem\_reserve: 0 0 12877 12877 Node 1 Normal free:9032kB min:9172kB low:11464kB high:13756kB active:12738108kB inactive:324096kB present:13186560kB pages\_scanned:32260117 all\_unreclaimable? yes lowmem\_reserve: 0 0 0 0 Node 1 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages\_scanned:0 all\_unreclaimable? no lowmem\_reserve: 0 0 0 0 Node 0 DMA: empty Node 0 DMA32: empty Node 0 Normal: 3_4kB 8_8kB 2_16kB 2_32kB 0_64kB 0_128kB 0_256kB 0_512kB 1_1024kB 1_2048kB 2_4096kB = 11436kB Node 0 HighMem: empty Node 1 DMA: 3_4kB 1_8kB 4_16kB 4_32kB 5_64kB 2_128kB 1_256kB 1_512kB 1_1024kB 0_2048kB 2_4096kB = 10772kB Node 1 DMA32: 16_4kB 6_8kB 0_16kB 0_32kB 1_64kB 1_128kB 1_256kB 0_512kB 0_1024kB 0_2048kB 13_4096kB = 53808kB Node 1 Normal: 36_4kB 3_8kB 4_16kB 3_32kB 0_64kB 0_128kB 0_256kB 1_512kB 0_1024kB 0_2048kB 2_4096kB = 9032kB Node 1 HighMem: empty 234104 pagecache pages Swap cache: add 33789697, delete 33795868, find 10561663/14701131, race 0+185 Free swap = 0kB Total swap = 524280kB Free swap: 0kB 8585216 pages of RAM 347762 reserved pages 4453 pages shared 98 pages swap cached Out of memory: Killed process 12651, UID 101, (mysqld). mysqld: page allocation failure. order:0, mode:0x201d2 Call Trace: [] \_\_alloc\_pages+0x2ef/0x308 [] \_\_do\_page\_cache\_readahead+0x96/0x179 [] filemap\_nopage+0x14c/0x360 [] \_\_handle\_mm\_fault+0x1fa/0xfaa [] do\_sync\_read+0xc7/0x104 [] do\_page\_fault+0x4cb/0x874 [] lock\_sock+0xa7/0xb2 [] \_spin\_lock\_bh+0x9/0x14 [] release\_sock+0x13/0xaa [] sock\_setsockopt+0x4db/0x4ed [] error\_exit+0x0/0x84 Thanks Manoj ---
**Author:** ![scott.nemes](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/scott.nemes/32/5_2.png) [@scott.nemes](https://forums.percona.com/u/scott.nemes)\ **Post date:** [June 20, 2012, 1:23pm UTC](https://forums.percona.com/t/mysql-restarted-automatically-because-of-out-of-memory/1833/2 "2012-06-20T13:23:45Z")
You can adjust the way the OOM killer handles the MySQL process, however the real issue is that you are giving MySQL too much memory. Based on the information you gave, you are giving MySQL 87.5% of your total memory just for the InnoDB buffer pool. On a dedicated MySQL server, it is normally recommended that you set the InnoDB buffer pool at 60-80% of your total memory at most. MySQL uses memory for other things besides the InnoDB buffer pool, so if you set that too high you will max yourself out pretty quickly. So before messing with the OOM killer, I would first address your memory usage which is the root of the problem.