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  1. Core Server
  2. SERVER-17299

Extraneous memory allocations in snappy hurt WiredTiger performance on Windows

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    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL
    • Backport Completed:
    • Steps To Reproduce:
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      I have 50 threads bulk inserting 100 <1k documents as fast as Mongo will take them.

      Using the MMap engine doesn't show this behavior. Right now, after running for ~8 minutes, my cpu is sitting at 23% and the insert rate is at 11k/s.

      I don't know if this is expected or not, but it seems like quite a dramatic drop off.

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      I have 50 threads bulk inserting 100 <1k documents as fast as Mongo will take them. Using the MMap engine doesn't show this behavior. Right now, after running for ~8 minutes, my cpu is sitting at 23% and the insert rate is at 11k/s. I don't know if this is expected or not, but it seems like quite a dramatic drop off.

      Description

      WiredTiger starts at an insertion rate of 40k/sec, and slows down to 15k/sec within 2 minutes.

      System memory is not exhausted.

      Specifically the CPU% appears to drop from 100% quite quickly and insert times (for the individual bulk inserts) grows.

      MongoStat doesn't appear to show any specific resource limit, nor do I see anything obvious.

      Using the C# driver 2.0.0-beta2.

      Please see https://groups.google.com/forum/#!topic/mongodb-user/DMa24b2TqKM

        Attachments

        1. MongoPerfTest.7z
          8.77 MB
        2. mongo8.png
          mongo8.png
          832 kB
        3. mongo7.png
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        4. mongo6.png
          mongo6.png
          1.06 MB
        5. mongo5.png
          mongo5.png
          1.05 MB
        6. mongo4.png
          mongo4.png
          1.05 MB
        7. mongo3.png
          mongo3.png
          375 kB
        8. mongo2.png
          mongo2.png
          381 kB
        9. mongo1.png
          mongo1.png
          302 kB

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                Updated:
                Resolved: