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  1. Core Server
  2. SERVER-20716

Slow listDatabases with WT

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: 3.0.6
    • Fix Version/s: None
    • Component/s: WiredTiger
    • Labels:
      None
    • Operating System:
      Linux

      Description

      On instance with more than 2k databases, a listDatabase take more than 11s :

      2015-10-01T15:01:24.173+0000 I COMMAND  [conn3164] command admin.$cmd command: listDatabases { listDatabases: 1.0 } keyUpdates:0 writeConflicts:0 numYields:0 reslen:189925 locks:{ Global: { acquireCount: { r: 5908 } }, Database: { acquireCount: { r: 2954 } } } 11609ms
      

      Tested on several instances :

      2015-10-01T15:02:41.537+0000 I COMMAND  [conn4713] command admin.$cmd command: listDatabases { listDatabases: 1.0 } keyUpdates:0 writeConflicts:0 numYields:0 reslen:213799 locks:{ Global: { acquireCount: { r: 6626 } }, Database: { acquireCount: { r: 3313 } } } 13618ms
      2015-10-01T15:03:10.178+0000 I COMMAND  [conn3400] command admin.$cmd command: listDatabases { listDatabases: 1.0 } keyUpdates:0 writeConflicts:0 numYields:0 reslen:187243 locks:{ Global: { acquireCount: { r: 5826 } }, Database: { acquireCount: { r: 2913 } } } 10917ms
      2015-10-01T15:03:47.616+0000 I COMMAND  [conn316099] command admin.$cmd command: listDatabases { listDatabases: 1.0 } keyUpdates:0 writeConflicts:0 numYields:0 reslen:192677 locks:{ Global: { acquireCount: { r: 5996 } }, Database: { acquireCount: { r: 2998 } } } 11979ms
      

      On another instance, running in 2.6 with mmapv1, listing about 8x more databases take less than 1s :

      2015-10-01T15:07:56.751+0000 [conn224132] command admin.$cmd command: listDatabases { listDatabases: 1.0 } keyUpdates:0 numYields:0 locks(micros) R:23663 r:128494 reslen:1300875 866ms
      

      Seems related to SERVER-17078

      Mongo version : 3.0.6
      OS : Linux / Ubuntu 14.04
      Storage configuration :
      storageEngine = wiredTiger
      wiredTigerCollectionBlockCompressor = snappy
      wiredTigerCacheSizeGB = 3

        Attachments

        1. dbv.log
          0.1 kB
          Anthony Brodard
        2. mongod.log
          17.53 MB
          Anthony Brodard
        3. ss.log
          375 kB
          Anthony Brodard

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              Assignee:
              Unassigned
              Reporter:
              anthony@brodard.me Anthony Brodard
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                Dates

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                Updated:
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