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  1. JDK
  2. JDK-8225797

OldObjectSample event creates unexpected amount of checkpoint data

    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: 11, 12, 13
    • Fix Version/s: 14
    • Component/s: hotspot
    • Subcomponent:
      jfr
    • Resolved In Build:
      b15

      Description

      Recordings where stackTrace has been enabled for OldObjectSample events creates an unexpected amount of data.

      For example, a recording where OldObjectSample is disabled is 2 MB while one where enabled and stackTrace=true becomes 10 MB. Most likely excessive (or redundant) information is written down. 'jfr summary' reveals that the space is taken by the checkpoint event

      The parser log shows a pattern where a large checkpoint happens multiple times. See attached log.txt

      [0.699s][trace][jfr,system,parser] New constant pool: startPosition=12945672, size=370710, deltaToNext=-11695, flush=false, poolCount=6
      [0.699s][trace][jfr,system,parser] Constant: java.lang.Class[1613]
      [0.700s][trace][jfr,system,parser] Constant: jdk.types.Package[281]
      [0.700s][trace][jfr,system,parser] Constant: jdk.types.Module[7]
      [0.700s][trace][jfr,system,parser] Constant: jdk.types.ClassLoader[13]
      [0.700s][trace][jfr,system,parser] Constant: jdk.types.Method[3775]
      [0.701s][trace][jfr,system,parser] Constant: jdk.types.Symbol[5470]
      ...

      Each large checkpoint is about 400 kB.

      The log can be reproduced like this:

      $ jfr -J-Xlog:jfr+system+parser=trace --events Dummy recording.jfr

      There could possibly be a similar problem where reference chains are recorded (cutoff > 0)

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              • Assignee:
                mgronlun Markus Grönlund
                Reporter:
                egahlin Erik Gahlin
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                Dates

                • Created:
                  Updated:
                  Resolved: