Diagnostics and Debugging

1. #MongoDBdays @asya999 #askAsya Diagnostics and Debugging Asya Kamsky Principal Solutions Architect, MongoDB

2. #MongoDBdays @asya999 #askAsya Diagnostics and Debugging Asya Kamsky Principal Solutions Architect, MongoDB

7. Understanding Crime Scene

9. “Data! Data! Data! I can't make bricks without clay.” -- Sherlock Holmes, The Adventure of the Copper Beeches 9

10. Gathering Data

11. “It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” -- Sherlock Holmes, A Scandal in Bohemia 11

13. “There is nothing like first-hand evidence.” -- Sherlock Holmes, A Study in Scarlet

14. Available Tools: %mongostat %mongotop > db.currentOp( ), db.serverStatus( ) > rs.status( ) > sh.status( )

15. Available Tools: %mongostat %mongotop > db.currentOp( ), db.serverStatus( ) > rs.status( ) > sh.status( ) MongoDB Management Service (MMS) Monitoring

16. Available Tools: MongoDB Management Service (MMS) Monitoring

20. mongod logs

21. mongod logs Tue Jul 30 19:15:27.898 [conn2] query test.docs query: { query: { _id: { $gt: ObjectId('51da44a8a4435e3d7174b696') } }, orderby: { ts: 1.0 } } ntoreturn:10 ntoskip:0 nscanned:9235093 scanAndOrder:1 keyUpdates:0 numYields:5 locks(micros) r:6919962 nreturned:1 reslen:360 3578ms

22. mongod logs

23. mongod logs

24. "It is of the highest importance ... to be able to recognize, out of a number of facts, which are incidental and which vital. " Sherlock Holmes, The Reigate Puzzle

27. https://github.com/rueckstiess/mtools by Thomas Rückstieß

28. mtools • mloginfo • mlogfilter • mplotqueries • mlogvis • mlaunch

29. mtools • mloginfo • mlogfilter • mplotqueries

30. mloginfo source: logs/mongodb.log.2014-05-04T15-52-59 start: 2014 May 02 00:29:21 end: 2014 May 04 15:52:59 date format: iso8601-local length: 17091234 binary: mongod version: 2.6.0 ------------------------------------------ source: logs/mongodb.log.2014-05-04T15-53-06 start: 2014 May 02 00:29:25 end: 2014 May 04 15:53:06 date format: iso8601-local length: 13696471 binary: mongod version: 2.6.0

31. mplotqueries $mplotqueries--help usage: mplotqueries[OPTIONS] [logfile[logfile...]] A script to plot various information from logfiles. ...

32. mplotqueries $ mplotqueries--help usage: mplotqueries[OPTIONS] [logfile[logfile...]] A script to plot various information from logfiles. ... optional arguments: --type{nscanned/n,rsstate,connchurn,durline,histogram,range,scatter,event} type of plot (default=scatter with --yaxisduration)

39. mplotqueries $ mplotqueries--help usage: mplotqueries[OPTIONS] [logfile[logfile...]] A script to plot various information from logfiles. ... optional arguments: --type{nscanned/n,rsstate,connchurn,durline,histogram,range,scatter,event} type of plot (default=scatter with --yaxisduration) --group GROUP specify value to group on. All basic plot types can group on 'namespace', 'operation', 'thread', 'pattern' ...

41. "... what is out of the common is usually a guide rather than a hindrance." — Sherlock Holmes, A Study in Scarlet

42. The Adventure of the Missing Three-Quarter (Indexes)

43. mloginfo $ mloginfofirstmongo.log source: firstmongo.log start: 2014 Jun 10 11:19:54 end: 2014 Jun 17 17:14:15 date format: iso8601-local length: 14170668 binary: mongod version: 2.6.1 mloginfofirstmongo.log--queries

44. mloginfo $mloginfofirstmongo.log source: firstmongo.log start: 2014 Jun 10 11:19:54 end: 2014 Jun 17 17:14:15 date format: iso8601-local length: 14170668 binary: mongod version: 2.6.1 mloginfofirstmongo.log–-queries namespace pattern count max (ms) mean (ms) 95%-ile(ms) sum (ms) db1.request {"requestSender": 1} 29 350161 93828 339441.2 2721018 db1.request {"curRoute": 1,"isAdv": 1 } 169 9585 3942 6324.2 666302 db1.report {"deliveryTime": 1} 9 111421 71536 106609.4 643829 db2.report {"deliveryTime": 1} 10 85267 60363 81508.15 603634 db3.report {"deliveryTime": 1} 10 72071 53062 70781.3 530624 db1.pending {"sentTime": 1, "status": 1} 9 108734 38013 88470.4 342117

45. mplotqueries % mplotqueriesfirstmongo.log--type nscanned/n

46. mplotqueries % mplotqueriesfirstmongo.log--type nscanned/n

47. mplotqueries % mplotqueriesfirstmongo.log--type nscanned/n 2014-06-17T17:13:34.235 [conn1569841] query db1.coll query: { time: { $lt: "2014-06-17 17:13:31", $gte: "2014-06-17 17:04:31" } } planSummary: COLLSCAN ntoreturn:0 ntoskip:0 nscanned:5169727nscannedObjects:5169727 keyUpdates:0 numYields:12492 locks(micros) r:37736571 nreturned:72reslen:32707 30129ms

50. mplotqueries % mplotqueriesfirstmongo.log--type nscanned/n 2014-06-17T17:13:34.235 [conn1569841] query db1.coll query: { time: { $lt: "2014-06-17 17:13:31", $gte: "2014-06-17 17:04:31" } } planSummary: COLLSCAN ntoreturn:0 ntoskip:0 nscanned:5169727nscannedObjects:5169727 keyUpdates:0 numYields:12492 locks(micros) r:37736571 nreturned:72reslen:32707 30129ms 2014-06-17T17:13:47.607 [conn1569990] query db2.coll query: { time: { $lt: "2014-06-17 17:14:05", $gte: "2014-06-17 17:05:05" }, status: 8 } planSummary: COLLSCAN ntoreturn:0 ntoskip:0 nscanned:2057564nscannedObjects:2057564 keyUpdates:0 numYields:5008 locks(micros) r:11557172 nreturned:56reslen:18745 13086ms

53. The Sign of Four (Shards)

54. % mplotqueriesupdates?.log

59. "Eliminate all other factors, and the one which remains must be the truth." Sherlock Holmes -The Sign of Four 59

60. The Case of Identity

64. % mplotqueries–type histogram –group namespace –bucketSize3600

71. The Stockbroker's Clerk's Query

73. % mplotqueries–type connchurn

86. "We balance probabilities and choose the most likely. It is the scientific use of the imagination." Sherlock Holmes, The Hound of the Baskervilles With profound thanks to: Sir Arthur Conan Doyle (1859-1930)

87. #MongoDBdays @asya999 Thank You Asya Kamsky MongoDB, Inc. http://askasya.com/ http://www.kamsky.org/

Diagnostics and Debugging

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