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  1. Core Server
  2. SERVER-20201

Performance drop over time when running with enableReplSnapshotThread=true under insert only workload

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: WiredTiger
    • Labels:
    • Backwards Compatibility:
      Fully Compatible
    • Steps To Reproduce:
      Hide

      Replica set
      Workload - Hammer.mongo, insert only profile w/ write majority

      %MongoD%\mongod --wiredTigerCacheSizeGB 3 --replSet EitanRs3b --dbpath f:\data\db1 --logpath h:\data\rs3primary.txt --storageEngine wiredTiger --port 5002 --setParameter enableReplSnapshotThread=true

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      Replica set Workload - Hammer.mongo, insert only profile w/ write majority %MongoD%\mongod --wiredTigerCacheSizeGB 3 --replSet EitanRs3b --dbpath f:\data\db1 --logpath h:\data\rs3primary.txt --storageEngine wiredTiger --port 5002 --setParameter enableReplSnapshotThread=true

      Description

      Environment:

      2 member replica set (Windows)
      db version v3.1.8-pre-
      git version: 9b054f00326b23a87ba0571cbd8997b91fe5ce16

      Storage size: 13 GB
      Workload:

      1. Hammer.mongo, insert only profile with write concern majority
      2. 16 threads
      3. Execution time 12 hours

      Problem:

      • The same workload w/ enableReplSnapshotThread=false produce significant better throughput - See compare.png

      The profiler indicates high CPU as results of __wt_tree_walk function that accountable for 80.83% of the CPU time - See profiler.png

        Attachments

        1. 318.html
          2.88 MB
        2. Compare.png
          Compare.png
          9 kB
        3. profiler.png
          profiler.png
          29 kB
        4. rs3primary.txt
          27.43 MB

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                Dates

                • Created:
                  Updated:
                  Resolved: