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  1. Core Server
  2. SERVER-20104

WT high memory usage due to high amount of free memory accumulated by TCMalloc

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Done
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: Performance, WiredTiger
    • Labels:
    • Operating System:
      ALL
    • Steps To Reproduce:
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      mongod --dbpath=d:\mongo --port=27200 --wiredTigerCacheSizeGB=3 --wiredTigerJournalCompressor=zlib --wiredTigerCollectionBlockCompressor=zlib

      User workload (Nick J)

      Show
      mongod --dbpath=d:\mongo --port=27200 --wiredTigerCacheSizeGB=3 --wiredTigerJournalCompressor=zlib --wiredTigerCollectionBlockCompressor=zlib User workload (Nick J)

      Description

      Environment:

      • Stand alone mongod
      • 3.1.6v
      • WiredTiger configured with zlib compression and 3GB cache size

      Observation/Issues:

      1. When running w/ 100 + threads, WT cache reached to 8GB (2.6 x original cache size).
      1. When running w/ 9 threads, WT cache reached to 5GB (1.6 x original cache size).

      Breakdown of the 5G memory highlight the followings:

      3 GB in the cache size (as expected)
      1.7 GB - Current_total_thread_cache_bytes (MB) (higher than expectation)
      0.45 GB - Total central_cache_free_bytes (MB) (higher than expectation)

      Problem: Our memory cache policy set for 1GB free, however the machine accumulate memory above this threshold.

        Attachments

        1. 100threads.html
          4.39 MB
          Eitan Klein
        2. 100threads.png
          104 kB
          Eitan Klein
        3. 3.1.6-3Gcache.html
          4.44 MB
          Eitan Klein
        4. buildInfo.txt
          1 kB
          Rakhi Meaheshwari
        5. collStatsLocalOplog.txt
          7 kB
          Rakhi Meaheshwari
        6. getCmdLineOpts.txt
          0.9 kB
          Rakhi Meaheshwari
        7. hostInfo.txt
          1 kB
          Rakhi Meaheshwari
        8. rsStatus.txt
          2 kB
          Rakhi Meaheshwari
        9. serverStatus.txt
          22 kB
          Rakhi Meaheshwari
        10. win_tcmalloc_agg.png
          48 kB
          Alexander Gorrod
        11. win_tcmalloc_default.png
          48 kB
          Alexander Gorrod
        12. win_tcmalloc24.png
          49 kB
          Alexander Gorrod

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              Assignee:
              backlog-server-execution Backlog - Execution Team
              Reporter:
              eitan.klein Eitan Klein
              Participants:
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                Dates

                Created:
                Updated:
                Resolved: