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IT24426: "java.io.IOException: Too many open files" errors from MQ v7.5 queue manager when using MQ Telemetry

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APAR status

  • Closed as program error.

Error description

  • FDCs are created with a probe ID XR013004, and an exception and
    stack like:
    
    |   |   Cause:1       :-  java.io.IOException: Too many open
    files
    |   |   Message:1     :-  Too many open files
    |   |   StackTrace:1  :-  java.io.IOException: Too many open
    files
    |   |   	at
    sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
    |   |   	at
    sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImp
    l.java:191)
    |   |   	at
    com.ibm.mq.communications.NonBlockingListener.run(NonBlockingLis
    tener.java:263)
    |   |   	at java.lang.Thread.run(Thread.java:767)
    
    The content from these FDCs may be written to the mqxr.stderr
    file instead if the lack of available file handles means that
    new FDCs cannot be created.
    
    A list of open files for the server shows that many thousands of
    instances of the same file are being held open by the MQXR
    service JVM process - for instance an lsof output on Linux would
    show thousands of instances like:
    
    java       4792  mqm 3807r   REG              253,0     2518
    1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
    java       4792  mqm 3808r   REG              253,0     2518
    1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
    java       4792  mqm 3809r   REG              253,0     2518
    1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
    java       4792  mqm 3810r   REG              253,0     2518
    1443685 /opt/mqm/mqxr/SDK/WebContent/index.html
    etc
    

Local fix

  •  Restarting the XR service JVM would also have cleared this up -
    would have to be the entire server, not just the channel though
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of IBM MQ Telemetry, with HTTP enabled
    on an MQTT channel, making HEAD requests on the hostname and
    port for that channel
    
    
    Platforms affected:
    Windows, Linux on x86-64, AIX
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    For each HEAD request received by the HTTP enabled MQTT channel,
    a file handle was being opened for each response created to
    return to the requesting client. This open file handle was never
    closed off.
    

Problem conclusion

  • Any file handles opened as a result of creating the responses to
    HTTP HEAD requests are now closed, and there is no longer a
    buildup of open file handles.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.5       7.5.0.9
    v8.0       8.0.0.11
    v9.0 LTS   9.0.0.5
    v9.1 CD    9.1.1
    v9.1 LTS   9.1.0.1
    
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
    
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
    ---------------------------------------------------------------
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT24426

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7241

  • Reported release

    750

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-03-19

  • Closed date

    2018-06-08

  • Last modified date

    2018-07-20

  • 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

    WMQ BASE MULTIP

  • Fixed component ID

    5724H7241

Applicable component levels



Document information

More support for: WebSphere MQ
APAR / Maintenance

Software version: 7.5

Reference #: IT24426

Modified date: 20 July 2018


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