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  1. Core Server
  2. SERVER-32886

Unnecessary sleeps during chunk migration

    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 3.4.14, 3.6.4, 3.7.3
    • Affects Version/s: 3.2.18, 3.4.10, 3.6.2
    • Component/s: Sharding
    • None
    • Fully Compatible
    • ALL
    • v3.6, v3.4
    • Sharding 2018-02-12, Sharding 2018-02-26

      From visual inspection of the chunk migration code, there are at least 3 places where nodes can unnecessarily sleep for up to a second:

      These sleeps unnecessarily increase the length of the balancer round, pollute the logs and on top of that could actually cause more mods to accumulate on the donor, potentially increasing the duration of the critical section catch-up phase.

      Most likely they are artifacts of MMAP V1 where chunk migration was intentionally slowed down in order not to interfere with live workload, but no longer make sense for WT. If we remove them we should still preserve some comparable throttle for MMAP V1.

            janna.golden@mongodb.com Janna Golden
            kaloian.manassiev@mongodb.com Kaloian Manassiev
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