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  1. Core Server
  2. SERVER-43069

Ops that are slow to apply don't condition on slowOpSampleRate

    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.3.4
    • Affects Version/s: 3.6.14, 4.0.12, 4.2.0
    • Component/s: None
    • Fully Compatible
    • ALL
    • Repl 2020-02-10
    • 39

      Here's the code in question: https://github.com/mongodb/mongo/blob/r3.6.14/src/mongo/db/repl/sync_tail.cpp#L335-L351

      That should be doing something similar to https://github.com/mongodb/mongo/blob/r3.6.14/src/mongo/db/ops/write_ops_exec.cpp#L122-L124

      This behaviour is called out in https://docs.mongodb.com/manual/release-notes/4.2/#slow-oplog, though I don't see any discussion on SERVER-32146 or DOCS-12178 for whether sampling was considered.

      There's also a couple other places where this might need to be checked:

      It's possible a better fix would be to decouple slowOpSampleRate and slowms, such that you log all slow operations but then subject non-slow ops to sampling.

            xuerui.fa@mongodb.com Xuerui Fa
            bartle David Bartley
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