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  1. Core Server
  2. SERVER-24207

Substantial excess allocated memory and stall in YCSB insert workload associated with very large page

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Gone away
    • Affects Version/s: 3.3.5, 3.3.6
    • Fix Version/s: None
    • Component/s: WiredTiger
    • Labels:

      Description

      • 64 GB memory, 24 cpus (12 cores)
      • mongod 3.3.5, standalone, 45 GB cache
      • YCSB workload as follows (in file repro.ycsb):

        fieldcount=3
        recordcount=800000000
        operationcount=400000000
        workload=com.yahoo.ycsb.workloads.CoreWorkload
         
        readallfields=true
         
        readproportion=0.5
        updateproportion=0.5
        scanproportion=0
        insertproportion=0
         
        requestdistribution=zipfian
        

        run as follows:

        ycsb load mongodb -s -P repro.ycsb -threads 30 -p batchsize=1000
        

      Some key metrics from a run:

      • stall from A-B immediately followed by
        • large jump in pages held in cache
        • very large maximum page size at eviction (about 10 GB)
        • immediate large jump in excess allocated memory of about the same size (11 GB)
        • excess immediately begins to decline
      • other stalls, e.g. C-D, appear to be associated with cache exceeding configured maximum (49 GB in cache vs 46 GB configured)

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                  Updated:
                  Resolved: