Workloads evict internal pages unexpectedly

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    • Type: Bug
    • Resolution: Done
    • Priority: Major - P3
    • WT2.7.0
    • Affects Version/s: None
    • Component/s: None
    • None
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      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

            Assignee:
            Unassigned
            Reporter:
            Alexander Gorrod
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              Created:
              Updated:
              Resolved: