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  1. WiredTiger
  2. WT-2260

Workloads evict internal pages unexpectedly

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: WT2.7.0
    • Labels:
      None

      Description

      We have noticed that some workloads are evicting internal pages when there are other candidates available.

      A wtperf configuration that results in internal page eviction, when there is plenty of space in cache for the internal structure is:

      conn_config="statistics=[all],statistics_log=(wait=10),cache_size=4G,eviction_trigger=85,eviction_target=70,eviction_dirty_trigger=85,eviction_dirty_target=60"
      table_config="type=file,allocation_size=4KB,internal_item_max=1433,internal_key_truncate=true,internal_page_max=16KB,leaf_item_max=1433,leaf_page_max=4KB,prefix_compression=false,split_pct=75"
      create=true
      key_sz=24
      value_sz=900
      icount=30000000
      report_interval=5
      run_time=1200
      populate_threads=1
      threads=((count=1,reads=1,throttle=5000))
      

      Since the workload is read-only it's possible to rerun with create=false above, and not re-create the database between runs.

      Investigating stats towards the end of such a run I see:

      WT_TEST/WiredTigerStat.04.14:Dec 04 14:11:10 2728133 WT_TEST cache: internal pages evicted
      

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              • Assignee:
                Unassigned
                Reporter:
                alexander.gorrod Alexander Gorrod
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                • Created:
                  Updated:
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