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PI69321: ENABLE VERBOSE GARBAGE COLLECTION BY DEFAULT

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Enable verbose garbage collection by default
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server for Distributed operating systems.   *
    ****************************************************************
    * PROBLEM DESCRIPTION: Verbose garbage collection (verboseGC)  *
    *                      is disabled by default.                 *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Staring in version 9.0.0.3 WebSphere Application Server for
    Distributed enables verboseGC by default for the Application
    Server, Node Agent, and Deployment Manager server types; and
    when enabled, WebSphere Application Server will log
    verboseGC output to 10 sequential, rotating (i.e. rolling)
    "verbosegc" files which cumulatively consume about 100M of
    disk space per server process.
    This is a change in default behavior from previous
    releases wherein verboseGC is disabled by default for all
    server types, and when enabled, verboseGC output
    writes to the native process logs.
    "Verbose garbage collection" (verboseGC) is a setting in the
    Java virtual machine configuration for a server type, such as
    a Deployment Manager or Application Server.  When verboseGC is
    enabled in a server configration in releases prior to
    9.0.0.3, WAS supplies the standard java option "-verbose:gc"
    to the java command line when launching the server.  In
    9.0.0.3 when verboseGC is enabled WAS supplies the following
    standard and non-standard java command line arguments when
    launching a server.
    On Windows, Linux, AIX:
    -verbose:gc
    -Xverbosegclog:${SERVER_LOG_ROOT}\verbosegc.%seq.log,10,7000
    On Solaris, HP-UX:
    -verbose:gc
    -Xloggc:${SERVER_LOG_ROOT}\verbosegc.log
    -XX:+UseGCLogFileRotation
    -XX:NumberOfGCLogFiles=10
    -XX:GCLogFileSize=10M
    -XX:+PrintGCDateStamps
    -XX:+PrintGCDetails
    These options direct the JVM to write verboseGC diagnostic
    data to as many as 10 rolling "verbosegc" logs which
    cumulatively consume about 100M of file space.  The logs are
    created in the ${SERVER_LOG_ROOT} directory alongside the
    other server logs.  Notice that, on Windows, AIX, and Linux,
    the options specify 7000 garage collection events per log.
    Because the size of GC events will vary, the amount of
    cumulative file space consumed by verbosegc logs will also
    vary on these platforms.
    To revert verbose GC logging behavior to that of previous
    releases, disable the verbose garbage collection setting
    in the server's Java virtual machine configuration and enter
    the standard Java command-line option "-verbose:gc" (unquoted)
    in the Generic JVM Arguments field of the same Java Virtual
    Machine configuration.  If the Generic JVM Arguments field
    contains no additional arguments that control verbose garbage
    collection logging, then the server will direct verboseGC
    diagnostic data to a native process log.
    

Problem conclusion

  • VerboseGC diagnostic data is critical to troubleshooting
    memory and performance problems, and the overhead is generally
    very low.  APAR PI69321 enables verboseGC by default to ensure
    diagnostic data is immediately available when such problems
    occur; and it redirects verboseGC output to rotating logs to
    both limit the amount of data collected and to reduce the risk
    that native process logs exhaust the available file space over
    the life of a server process.
    
    The fix for this APAR is currently targeted for inclusion in
    fix pack 9.0.0.3.  Please refer to the Recommended Updates
    page for delivery information:
    http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI69321

  • Reported component name

    WEBS APP SERV N

  • Reported component ID

    5724H8800

  • Reported release

    900

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-09-16

  • Closed date

    2017-02-22

  • Last modified date

    2017-02-22

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    WEBS APP SERV N

  • Fixed component ID

    5724H8800

Applicable component levels

  • R900 PSY

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"900","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
18 October 2021