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  1. Core Server
  2. SERVER-18677

Throughput drop during transaction pinned phase of checkpoints under WiredTiger (larger data set)

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Details

    • Bug
    • Status: Closed
    • Major - P3
    • Resolution: Done
    • 3.1.3
    • None
    • WiredTiger
    • None
    • Fully Compatible
    • ALL

    Description

      • 132 GB memory, 32 processors, slowish SSDs, 20 GB WT cache
      • YCSB 10 fields/doc, 50/50 workload (zipfian distribution), 20 threads
      • data set size varies - see tests below
        • 10M docs, data set ~12 GB (but cache usage can be double that)
        • 20M docs, data set ~23 GB (but cache usage can be double that)

      In SERVER-18315 an issue was reported in 3.0.2 during the "transaction pinned" phase of checkpoints (B-C) with a 10M document data set:

      This was fixed in 3.1.3:

      However if the data set is increased to 20M documents a similar problem still appears in 3.1.3. Based on the shapes of the curves it appears this may be a little different issue: in SERVER-18315 the throughput dropped in proportion to the rise in "range of transactions pinned" but that does not seem to be the case here.

      (Note: C-D is a different issue - see SERVER-18674).

      Attachments

        1. try-33.png
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        2. try-49a.png
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        3. try-52.png
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        4. try-49b.png
          try-49b.png
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        5. try-64-gdb.png
          try-64-gdb.png
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              david.hows David Hows
              bruce.lucas@mongodb.com Bruce Lucas
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              Dates

                Created:
                Updated:
                Resolved: