Uploaded image for project: 'Core Server'
  1. Core Server
  2. SERVER-21887

$sample takes disproportionately long time on newly created collection

    Details

    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      Linux
    • Backport Completed:
    • Steps To Reproduce:
      Hide
      1. Download the attached repro.js
      2. Run test with wiredTiger storage engine ($sample takes about 5200 milliseconds for me)

        python buildscripts/resmoke.py repro.js
        

      3. For a baseline of some sort, compare to timing on mmapv1 (about 550 milliseconds)

        python buildscripts/resmoke.py --storageEngine=mmapv1 repro.js
        

      Show
      Download the attached repro.js Run test with wiredTiger storage engine ($sample takes about 5200 milliseconds for me) python buildscripts/resmoke.py repro.js For a baseline of some sort, compare to timing on mmapv1 (about 550 milliseconds) python buildscripts/resmoke.py --storageEngine=mmapv1 repro.js

      Description

      Even though SERVER-19182 and SERVER-19183 exist, I have a collection of one million documents on which $sample takes very long time. This shows even on collections with only 10K documents.

      This only happens to collection that was just created. Restarting mongod process "fixes" this symptom.

        Attachments

        1. metrics.2015-12-14T16-20-52Z-00000
          117 kB
        2. perf-sample.png
          perf-sample.png
          121 kB
        3. repro.js
          0.4 kB
        4. Screenshot 2015-12-14 10.07.31.png
          Screenshot 2015-12-14 10.07.31.png
          399 kB

          Issue Links

            Activity

              People

              • Votes:
                0 Vote for this issue
                Watchers:
                13 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: