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  1. Core Server
  2. SERVER-41291

Oldest timestamp not always advanced with --enableMajorityReadConcern=false, on secondary nodes

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Details

    • Bug
    • Status: Closed
    • Critical - P2
    • Resolution: Fixed
    • 4.0.5, 4.0.9
    • 4.0.10
    • Storage
    • None
    • Fully Compatible
    • ALL
    • Execution Team 2019-06-03

    Description

      Run the following against a replica set with majority read concern disabled. It generates bursts of updates spaced 15 seconds apart.

      function update() {
          for (var i = 0; i < 1000; i++)
              db.c.insert({x: 0})
          for (var x = 0; ; x++) {
              db.c.updateMany({}, {$set: {x: x}})
              if (x%20 == 1)
                  sleep(15000)
          }
      }
      

      FTDC shows the following:

      During the bursts we are executing a couple hundred batches per second, but the oldest timestamp is not advanced on every batch, and in fact may not be advanced for minutes at a time. This can cause a large amount of data to be pinned in cache.

      Attachments

        1. oldest.png
          144 kB
          Bruce Lucas

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              milkie@mongodb.com Eric Milkie
              bruce.lucas@mongodb.com Bruce Lucas
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                Created:
                Updated:
                Resolved: