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  1. Core Server
  2. SERVER-18788

wiredtiger 10x slower than mmap replica instance

    • Type: Icon: Bug Bug
    • Resolution: Done
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Performance
    • None
    • Environment:
    • Linux

      When we switch primaries to be the wiredTiger instances, while there
      is almost no additional stress on the machines, the time taken for
      queries goes out of whack.

      For our homepage, https://www.shopcade.com/, to load for a logged in
      user (me), about 200 mongo queries execute in 200 ms. Please find
      attached a screen capture (homepage-mongo-debug.png) from our in-house
      web-request level profiling tool.
      When we switch our primaries to the wiredTiger instances, the time on
      average for each query goes up by a factor of 10/20 times. There
      aren't a few queries that are slow, but all of them, compared to MMAP.
      The total load time for the page goes from 1-2 seconds into 10s of
      seconds.

      I've got only marginal improvements changing to the following configuration
      wiredTiger:
      collectionConfig:
      blockCompressor: "none"
      engineConfig:
      cacheSizeGB: 180
      journalCompressor: "none"
      indexConfig:
      prefixCompression: false

        1. Screenshot 2015-06-04 10.38.20.png
          Screenshot 2015-06-04 10.38.20.png
          85 kB
        2. Screenshot 2015-06-04 10.33.37.png
          Screenshot 2015-06-04 10.33.37.png
          80 kB
        3. mongo-engine-comparisons.zip
          49.30 MB
        4. mongod.log
          499 kB

            Assignee:
            sam.kleinman Sam Kleinman (Inactive)
            Reporter:
            vain navin kumar
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              Created:
              Updated:
              Resolved: