Estamos nos deparando com o assassino da OOM, apesar de quase metade da nossa memória estar sendo usada para o cache do FS. Estamos registrando estatísticas de memória uma vez por minuto (como relatado por cima), mas parece haver muita disponibilidade.
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Mem: 15339640k total, 15268304k used, 71336k free, 3152k buffers
Swap: 0k total, 0k used, 0k free, 6608384k cached
Mem: 15339640k total, 14855280k used, 484360k free, 13748k buffers
Swap: 0k total, 0k used, 0k free, 6481852k cached
[OOM killer: postgres killed]
Mem: 15339640k total, 8212200k used, 7127440k free, 32776k buffers
Swap: 0k total, 0k used, 0k free, 2394444k cached
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Detalhes da OOM do syslog:
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Jun 10 05:45:25 db kernel: [11209156.840462] wal-e invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0
Jun 10 05:45:25 db kernel: [11209156.840469] wal-e cpuset=/ mems_allowed=0
Jun 10 05:45:25 db kernel: [11209156.840474] Pid: 7963, comm: wal-e Not tainted 3.2.0-43-virtual #68-Ubuntu
Jun 10 05:45:25 db kernel: [11209156.840477] Call Trace:
Jun 10 05:45:25 db kernel: [11209156.840498] [<ffffffff81119711>] dump_header+0x91/0xe0
Jun 10 05:45:25 db kernel: [11209156.840502] [<ffffffff81119a95>] oom_kill_process+0x85/0xb0
Jun 10 05:45:25 db kernel: [11209156.840506] [<ffffffff81119e3a>] out_of_memory+0xfa/0x220
Jun 10 05:45:25 db kernel: [11209156.840511] [<ffffffff8111f823>] __alloc_pages_nodemask+0x8c3/0x8e0
Jun 10 05:45:25 db kernel: [11209156.840520] [<ffffffff81216e00>] ? noalloc_get_block_write+0x30/0x30
Jun 10 05:45:25 db kernel: [11209156.840528] [<ffffffff811566c6>] alloc_pages_current+0xb6/0x120
Jun 10 05:45:25 db kernel: [11209156.840534] [<ffffffff81116637>] __page_cache_alloc+0xb7/0xd0
Jun 10 05:45:25 db kernel: [11209156.840539] [<ffffffff81118602>] filemap_fault+0x212/0x3c0
Jun 10 05:45:25 db kernel: [11209156.840553] [<ffffffff81138c32>] __do_fault+0x72/0x550
Jun 10 05:45:25 db kernel: [11209156.840557] [<ffffffff8113c2ea>] handle_pte_fault+0xfa/0x200
Jun 10 05:45:25 db kernel: [11209156.840562] [<ffffffff8100638e>] ? xen_pmd_val+0xe/0x10
Jun 10 05:45:25 db kernel: [11209156.840567] [<ffffffff81005309>] ? __raw_callee_save_xen_pmd_val+0x11/0x1e
Jun 10 05:45:25 db kernel: [11209156.840571] [<ffffffff8113d559>] handle_mm_fault+0x269/0x370
Jun 10 05:45:25 db kernel: [11209156.840576] [<ffffffff8100a56d>] ? xen_force_evtchn_callback+0xd/0x10
Jun 10 05:45:25 db kernel: [11209156.840581] [<ffffffff8100ad42>] ? check_events+0x12/0x20
Jun 10 05:45:25 db kernel: [11209156.840589] [<ffffffff8165b3cb>] do_page_fault+0x14b/0x520
Jun 10 05:45:25 db kernel: [11209156.840594] [<ffffffff81160d64>] ? kmem_cache_free+0x104/0x110
Jun 10 05:45:25 db kernel: [11209156.840600] [<ffffffff811ba2c8>] ? ep_remove+0xa8/0xc0
Jun 10 05:45:25 db kernel: [11209156.840604] [<ffffffff811bb133>] ? sys_epoll_ctl+0xb3/0x3d0
Jun 10 05:45:25 db kernel: [11209156.840614] [<ffffffff81658035>] page_fault+0x25/0x30
Jun 10 05:45:25 db kernel: [11209156.840617] Mem-Info:
Jun 10 05:45:25 db kernel: [11209156.840618] Node 0 DMA per-cpu:
Jun 10 05:45:25 db kernel: [11209156.840622] CPU 0: hi: 0, btch: 1 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840624] CPU 1: hi: 0, btch: 1 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840627] CPU 2: hi: 0, btch: 1 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840629] CPU 3: hi: 0, btch: 1 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840631] Node 0 DMA32 per-cpu:
Jun 10 05:45:25 db kernel: [11209156.840634] CPU 0: hi: 186, btch: 31 usd: 30
Jun 10 05:45:25 db kernel: [11209156.840637] CPU 1: hi: 186, btch: 31 usd: 47
Jun 10 05:45:25 db kernel: [11209156.840639] CPU 2: hi: 186, btch: 31 usd: 15
Jun 10 05:45:25 db kernel: [11209156.840641] CPU 3: hi: 186, btch: 31 usd: 2
Jun 10 05:45:25 db kernel: [11209156.840643] Node 0 Normal per-cpu:
Jun 10 05:45:25 db kernel: [11209156.840646] CPU 0: hi: 186, btch: 31 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840648] CPU 1: hi: 186, btch: 31 usd: 14
Jun 10 05:45:25 db kernel: [11209156.840650] CPU 2: hi: 186, btch: 31 usd: 0
Jun 10 05:45:25 db kernel: [11209156.840653] CPU 3: hi: 186, btch: 31 usd: 1
Jun 10 05:45:25 db kernel: [11209156.840658] active_anon:3616567 inactive_anon:4798 isolated_anon:0
Jun 10 05:45:25 db kernel: [11209156.840660] active_file:98 inactive_file:168 isolated_file:20
Jun 10 05:45:25 db kernel: [11209156.840661] unevictable:1597 dirty:73 writeback:0 unstable:0
Jun 10 05:45:25 db kernel: [11209156.840662] free:16921 slab_reclaimable:17631 slab_unreclaimable:7534
Jun 10 05:45:25 db kernel: [11209156.840663] mapped:1614529 shmem:1613928 pagetables:124012 bounce:0
Jun 10 05:45:25 db kernel: [11209156.840666] Node 0 DMA free:7888kB min:4kB low:4kB high:4kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:7632kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
Jun 10 05:45:25 db kernel: [11209156.840681] lowmem_reserve[]: 0 4016 15112 15112
Jun 10 05:45:25 db kernel: [11209156.840686] Node 0 DMA32 free:48368kB min:4176kB low:5220kB high:6264kB active_anon:3776804kB inactive_anon:28kB active_file:0kB inactive_file:20kB unevictable:932kB isolated(anon):0kB isolated(file):0kB present:4112640kB mlocked:932kB dirty:0kB writeback:0kB mapped:1458536kB shmem:1458632kB slab_reclaimable:17604kB slab_unreclaimable:8088kB kernel_stack:1872kB pagetables:190616kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:437 all_unreclaimable? yes
Jun 10 05:45:25 db kernel: [11209156.840698] lowmem_reserve[]: 0 0 11095 11095
Jun 10 05:45:25 db kernel: [11209156.840703] Node 0 Normal free:11428kB min:11548kB low:14432kB high:17320kB active_anon:10689464kB inactive_anon:19164kB active_file:528kB inactive_file:652kB unevictable:5456kB isolated(anon):0kB isolated(file):80kB present:11362176kB mlocked:5456kB dirty:292kB writeback:0kB mapped:4999580kB shmem:4997080kB slab_reclaimable:52920kB slab_unreclaimable:22048kB kernel_stack:2584kB pagetables:305432kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:1974 all_unreclaimable? yes
Jun 10 05:45:25 db kernel: [11209156.840715] lowmem_reserve[]: 0 0 0 0
Jun 10 05:45:25 db kernel: [11209156.840720] Node 0 DMA: 2*4kB 3*8kB 1*16kB 3*32kB 3*64kB 3*128kB 2*256kB 1*512kB 2*1024kB 2*2048kB 0*4096kB = 7888kB
Jun 10 05:45:25 db kernel: [11209156.840752] Node 0 DMA32: 5813*4kB 2636*8kB 114*16kB 15*32kB 5*64kB 1*128kB 1*256kB 0*512kB 1*1024kB 0*2048kB 0*4096kB = 48372kB
Jun 10 05:45:25 db kernel: [11209156.840776] Node 0 Normal: 1888*4kB 10*8kB 46*16kB 4*32kB 3*64kB 2*128kB 1*256kB 1*512kB 0*1024kB 1*2048kB 0*4096kB = 11760kB
Jun 10 05:45:25 db kernel: [11209156.840788] 1615243 total pagecache pages
Jun 10 05:45:25 db kernel: [11209156.840790] 0 pages in swap cache
Jun 10 05:45:25 db kernel: [11209156.840801] Swap cache stats: add 0, delete 0, find 0/0
Jun 10 05:45:25 db kernel: [11209156.840803] Free swap = 0kB
Jun 10 05:45:25 db kernel: [11209156.840805] Total swap = 0kB
Jun 10 05:45:25 db kernel: [11209156.909794] 3934192 pages RAM
Jun 10 05:45:25 db kernel: [11209156.909804] 99282 pages reserved
Jun 10 05:45:25 db kernel: [11209156.909809] 18899146 pages shared
Jun 10 05:45:25 db kernel: [11209156.909811] 2198511 pages non-shared
Jun 10 05:45:25 db kernel: [11209156.909817] [ pid ] uid tgid total_vm rss cpu oom_adj oom_score_adj name
Jun 10 05:45:25 db kernel: [11209156.909835] [ 332] 0 332 4308 109 1 0 0 upstart-udev-br
Jun 10 05:45:25 db kernel: [11209156.909845] [ 346] 0 346 5384 271 2 -17 -1000 udevd
Jun 10 05:45:25 db kernel: [11209156.909851] [ 408] 0 408 5364 174 2 -17 -1000 udevd
...
Jun 10 05:45:25 db kernel: [11209156.910703] [ 7963] 111 7963 17456 2966 0 0 0 wal-e
Jun 10 05:45:25 db kernel: [11209156.910707] [ 7968] 111 7968 1639372 2351 3 0 0 postgres
Jun 10 05:45:25 db kernel: [11209156.910711] [ 7969] 111 7969 1639371 1934 2 0 0 postgres
Jun 10 05:45:25 db kernel: [11209156.910716] Out of memory: Kill process 12443 (postgres) score 418 or sacrifice child
Jun 10 05:45:25 db kernel: [11209156.910733] Killed process 12443 (postgres) total-vm:6555152kB, anon-rss:4600kB, file-rss:6396572kB
Jun 10 05:45:30 db kernel: [11209159.293083] postgres invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0
Jun 10 05:45:31 db kernel: [11209159.293091] postgres cpuset=/ mems_allowed=0
Jun 10 05:45:31 db kernel: [11209159.293095] Pid: 6508, comm: postgres Not tainted 3.2.0-43-virtual #68-Ubuntu
Jun 10 05:45:31 db kernel: [11209159.293098] Call Trace:
Jun 10 05:45:31 db kernel: [11209159.293111] [<ffffffff81119711>] dump_header+0x91/0xe0
Jun 10 05:45:31 db kernel: [11209159.293115] [<ffffffff81119a95>] oom_kill_process+0x85/0xb0
Jun 10 05:45:31 db kernel: [11209159.293119] [<ffffffff81119e3a>] out_of_memory+0xfa/0x220
...
Podemos tentar aumentar a resolução destes aproximadamente uma vez por segundo, mas haveria algum motivo para uma OOM aqui? (Vimos o link mas estamos trabalhando com quantidades absolutas de memória muito maiores, a maioria das quais é obtida pelo cache FS do kernel.)
Também incluindo partes relevantes do nosso postgresql.conf
abaixo:
shared_buffers = 6GB
effective_cache_size = 8GB