Thanks for the reply.
I've now updated the background writer settings to:
# - Background Writer -
bgwriter_delay = 200ms # 10-10000ms between rounds
bgwriter_lru_maxpages = 400 # 0-1000 max buffers written/round
bgwriter_lru_multiplier = 2.0 # 0-10.0 multipler on buffers scanned/round
checkpoint_segments = 128
checkpoint_timeout = 25min
It's still happening at the moment, this time without any checkpoint entries in the log :(
Below the output from vmstat. I'm not sure what to look for in there?
Thanks again,
Armand
$ sudo vmstat 5
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
2 0 0 485800 4224 44781700 0 0 167 91 1 0 21 1 78 0 0
7 0 0 353920 4224 44836176 0 0 6320 54 21371 12921 11 2 87 0 0
32 0 0 352220 4232 44749544 0 0 1110 8 19414 9620 6 42 52 0 0
3 0 0 363044 4232 44615772 0 0 59 1943 11185 3774 0 81 18 0 0
48 0 0 360076 4240 44550744 0 0 0 34 9563 5210 0 74 26 0 0
33 0 0 413708 4240 44438248 0 0 92 962 11250 8169 0 61 39 0 0
109 0 0 418080 4240 44344596 0 0 605 3490 10098 6216 1 49 50 0 0
58 0 0 425388 4240 44286528 0 0 5 10 10794 2470 1 91 8 0 0
53 0 0 435864 4240 44243000 0 0 11 0 9755 2428 0 92 8 0 0
12 0 0 440792 4248 44213164 0 0 134 5 7883 3038 0 51 49 0 0
3 0 0 440360 4256 44158684 0 0 548 146 8450 3930 2 27 70 0 0
2 0 0 929236 4256 44248608 0 0 10466 845 22575 14196 20 5 74 0 0
4 0 0 859160 4256 44311828 0 0 7120 61 20890 12835 12 1 86 0 0
4 0 0 685308 4256 44369404 0 0 6110 24 20645 12545 13 1 85 0 0
4 0 0 695440 4256 44396304 0 0 5351 1208 19529 11781 11 1 88 0 0
4 0 0 628276 4256 44468116 0 0 9202 0 19875 12172 9 1 89 0 0
6 0 0 579716 4256 44503848 0 0 3799 22 19223 11772 10 1 88 0 0
3 1 0 502948 4256 44539784 0 0 3721 6700 20620 11939 13 1 85 0 0
4 0 0 414120 4256 44583456 0 0 3860 856 19801 12092 10 1 89 0 0
6 0 0 349240 4256 44642880 0 0 6122 48 19834 11933 11 2 87 0 0
3 0 0 400536 4256 44535872 0 0 6287 5 18945 11461 10 1 89 0 0
3 0 0 364256 4256 44592412 0 0 5487 2018 20145 12344 11 1 87 0 0
7 0 0 343732 4256 44598784 0 0 4209 24 19099 11482 10 1 88 0 0
6 0 0 339608 4236 44576768 0 0 6805 151 18821 11333 9 2 89 0 0
9 1 0 339364 4236 44556884 0 0 2597 4339 19205 11918 11 3 85 0 0
24 0 0 341596 4236 44480368 0 0 6165 5309 19353 11562 11 4 84 1 0
30 0 0 359044 4236 44416452 0 0 1364 6 12638 6138 5 28 67 0 0
4 0 0 436468 4224 44326500 0 0 3704 1264 11346 7545 4 27 68 0 0
3 1 0 459736 4224 44384788 0 0 6541 8 20159 12097 11 1 88 0 0
8 1 0 347812 4224 44462100 0 0 12292 2860 20851 12377 9 1 89 1 0
1 0 0 379752 4224 44402396 0 0 5849 147 20171 12253 11 1 88 0 0
4 0 0 453692 4216 44243480 0 0 6546 269 20689 13028 12 2 86 0 0
8 0 0 390160 4216 44259768 0 0 4243 0 20476 21238 6 16 78 0 0
6 0 0 344504 4216 44336264 0 0 7214 2 20919 12625 11 1 87 0 0
4 0 0 350128 4200 44324976 0 0 10726 2173 20417 12351 10 1 88 0 0
2 1 0 362300 4200 44282484 0 0 7148 714 22469 14468 12 2 86 0 0
3 0 0 366252 4184 44311680 0 0 7617 133 20487 12364 9 1 90 0 0
6 0 0 368904 4184 44248152 0 0 5162 6 22910 15221 14 7 80 0 0
2 0 0 383108 4184 44276780 0 0 5846 1120 21109 12563 11 1 88 0 0
7 0 0 338348 4184 44274472 0 0 9270 5 21243 12698 10 1 88 0 0
24 0 0 339676 4184 44213036 0 0 6639 18 22976 12700 13 12 74 0 0
12 0 0 371848 4184 44146500 0 0 657 133 18968 7445 5 53 43 0 0
37 0 0 374516 4184 44076212 0 0 16 2 9156 4472 1 48 52 0 0
16 0 0 398412 4184 43971060 0 0 127 0 9967 6018 0 48 52 0 0
4 0 0 417312 4184 44084392 0 0 17434 1072 23661 14268 16 6 78 1 0
4 0 0 407672 4184 44139896 0 0 5785 0 19779 11869 11 1 88 0 0
9 0 0 349544 4184 44051596 0 0 6899 8 20376 12774 10 3 88 0 0
5 0 0 424628 4184 44059628 0 0 9105 175 24546 15354 13 20 66 1 0
2 0 0 377164 4184 44070564 0 0 9363 3 21191 12608 11 2 87 0 0
5 0 0 353360 4184 44040804 0 0 6661 0 20931 12815 12 2 85 0 0
4 0 0 355144 4180 44034620 0 0 7061 8 21264 12379 11 3 86 0 0
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
21 0 0 358396 4180 43958420 0 0 7595 1749 23258 12299 10 27 63 0 0
6 1 0 437480 4160 43922152 0 0 17565 14 17059 14928 6 18 74 2 0
6 0 0 380304 4160 43993932 0 0 10120 168 21519 12798 11 2 87 0 0
8 0 0 337740 4160 44007432 0 0 6033 520 20872 12461 11 1 88 0 0
13 0 0 349712 4132 43927784 0 0 6777 6 20919 12568 11 2 86 0 0
6 1 0 351180 4112 43899756 0 0 8640 0 22543 12519 11 10 78 0 0
6 0 0 356392 4112 43921532 0 0 6206 48 20383 12050 12 1 86 0 0
6 0 0 355552 4108 43863448 0 0 6106 3 21244 11817 9 9 82 0 0
3 0 0 364992 7312 43856824 0 0 11283 199 21296 12638 13 2 85 0 0
4 1 0 371968 7120 43818552 0 0 6715 1534 22322 13305 11 7 81 0 0
debug2: channel 0: window 999365 sent adjust 49211
12 0 0 338540 7120 43822256 0 0 9142 3 21520 12194 13 5 82 0 0
8 0 0 386016 7112 43717136 0 0 2123 3 20465 11466 8 20 72 0 0
8 0 0 352388 7112 43715872 0 0 10366 51 25758 13879 16 19 65 0 0
20 0 0 351472 7112 43701060 0 0 13091 10 23766 12832 11 11 77 1 0
2 0 0 386820 7112 43587520 0 0 482 210 17187 6773 3 69 28 0 0
64 0 0 401956 7112 43473728 0 0 0 5 10796 9487 0 55 44 0 0
On Tue, Apr 2, 2013 at 12:56 AM, Vasilis Ventirozos <v.ventirozos@xxxxxxxxx> wrote:
Hello, i think that your system during the checkpoint pauses all clients in order to flush all data from controller's cache to the disks if i were you i'd try to tune my checkpoint parameters better, if that doesn't work, show us some vmstat output please
Vasilis Ventirozos
---------- Forwarded message ----------
From: "Armand du Plessis" <adp@xxxxxxx>
Date: Apr 2, 2013 1:37 AM
Subject: [PERFORM] Problems with pg_locks explosion
To: "pgsql-performance" <pgsql-performance@xxxxxxxxxxxxxx>
Cc:[Apologies, I first sent this to the incorrect list, postgres-admin, in the event you receive it twice]
Hi there,I'm hoping someone on the list can shed some light on an issue I'm having with our Postgresql cluster. I'm literally tearing out my hair and don't have a deep enough understanding of Postgres to find the problem.What's happening is I had severe disk/io issues on our original Postgres cluster (9.0.8) and switched to a new instance with a RAID-0 volume array. The machine's CPU usage would hover around 30% and our database would run lightning fast with pg_locks hovering between 100-200.Within a few seconds something would trigger a massive increase in pg_locks so that it suddenly shoots up to 4000-8000. At this point everything dies. Queries that usually take a few milliseconds takes minutes and everything is unresponsive until I restart postgres.The instance still idles at this point. The only clue I could find was that it usually starts a few minutes after the checkpoint entries appear in my logs.Any suggestions would really be appreciated. It's killing our business at the moment. I can supply more info if required but pasted what I thought would be useful below. Not sure what else to change in the settings.Kind regards,ArmandIt's on Amazon EC2 -* cc2.8xlarge instance type* 6 volumes in RAID-0 configuration. (1000 PIOPS)60.5 GiB of memory
88 EC2 Compute Units (2 x Intel Xeon E5-2670, eight-core)
3370 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
EBS-Optimized Available: No**API name: cc2.8xlarge
postgresql.conffsync = offfull_page_writes = offdefault_statistics_target = 100maintenance_work_mem = 1GBcheckpoint_completion_target = 0.9effective_cache_size = 48GBwork_mem = 64MBwal_buffers = -1checkpoint_segments = 128shared_buffers = 32GBmax_connections = 800effective_io_concurrency = 3 # Down from 6
# - Background Writer -#bgwriter_delay = 200ms # 10-10000ms between rounds#bgwriter_lru_maxpages = 100 # 0-1000 max buffers written/round#bgwriter_lru_multiplier = 2.0 # 0-10.0 multipler on buffers scanned/round
$ freetotal used free shared buffers cachedMem: 61368192 60988180 380012 0 784 44167172-/+ buffers/cache: 16820224 44547968Swap: 0 0 0$ top -ctop - 21:55:51 up 12 days, 12:41, 4 users, load average: 6.03, 16.10, 24.15top - 21:55:54 up 12 days, 12:41, 4 users, load average: 6.03, 15.94, 24.06Tasks: 837 total, 6 running, 831 sleeping, 0 stopped, 0 zombieCpu(s): 15.7%us, 1.7%sy, 0.0%ni, 81.6%id, 0.3%wa, 0.0%hi, 0.6%si, 0.0%stMem: 61368192k total, 54820988k used, 6547204k free, 9032k buffer[ec2-user@ip-10-155-231-112 ~]$ sudo iostatLinux 3.2.39-6.88.amzn1.x86_64 () 04/01/2013 _x86_64_ (32 CPU)avg-cpu: %user %nice %system %iowait %steal %idle21.00 0.00 1.10 0.26 0.00 77.63Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtnxvda 0.21 5.00 2.22 5411830 2401368xvdk 98.32 1774.67 969.86 1919359965 1048932113xvdj 98.28 1773.68 969.14 1918288697 1048156776xvdi 98.29 1773.69 969.61 1918300250 1048662470xvdh 98.24 1773.92 967.54 1918544618 1046419936xvdg 98.27 1774.15 968.85 1918790636 1047842846xvdf 98.32 1775.56 968.69 1920316435 1047668172md127 733.85 10645.68 5813.70 11513598393 6287682313What bugs me on this is the throughput percentage on the volumes in Cloudwatch is 100% on all volumes.The problems seem to overlap with checkpoints.2013-04-01 21:31:35.592 UTC,,,26877,,5159fa5f.68fd,1,,2013-04-01 21:21:35 UTC,,0,LOG,00000,"checkpoint starting: time",,,,,,,,,""2013-04-01 21:40:35.033 UTC,,,26877,,5159fa5f.68fd,2,,2013-04-01 21:21:35 UTC,,0,LOG,00000,"checkpoint complete: wrote 100635 buffers (2.4%); 0 transaction log file(s) added, 0 removed, 1 recycled; write=539.439 s, sync=0.000 s, total=539.441 s; sync files=0, longest=0.000 s, average=0.000 s",,,,,,,,,""2013-04-01 21:41:35.093 UTC,,,26877,,5159fa5f.68fd,3,,2013-04-01 21:21:35 UTC,,0,LOG,00000,"checkpoint starting: time",,,,,,,,,""
