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PM74747: CONNECTIONS ARE NOT CLOSED AFTER AN UNEXPECTED EXCEPTION OCCURS

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Connections in the control region are not cleaned up properly
    when an unexpected exception is received completing an
    asynchronous read.
    Netstat conn will show connections for the control region in
    CLOSEWAIT.
    An example of an unexpected exception is this FFDC:
    FFDC Exception:java.lang.NullPointerException
    SourceId:com.ibm.ws.tcp.channel.ZAioTCPChannel ProbeId:300
    Reporter:com.ibm.ws.tcp.channel.impl.ZAioTCPChannel@11c3b761
    java.lang.NullPointerException
    at com.ibm.ws390.xmem.proxy.channel.XMemProxyCRInboundConnLink.
        destroyCommon(XMemProxyCRInboundConnLink.java:301)
    at com.ibm.ws390.xmem.proxy.channel.XMemProxyCRInboundConnLink.
        destroy(XMemProxyCRInboundConnLink.java:285)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.
        destroy(HttpInboundLink.java:158)
    at com.ibm.wsspi.channel.base.OutboundConnectorLink.
        destroy(OutboundConnectorLink.java:63)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPConnLink.
        destroyCommon(ZAioTCPConnLink.java:1060)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPConnLink.
        destroy(ZAioTCPConnLink.java:1020)
    at com.ibm.wsspi.channel.base.OutboundConnectorLink.
        close(OutboundConnectorLink.java:50)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.
        close(HttpInboundLink.java:781)
    at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.
        error(HttpICLReadCallback.java:134)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPReadRequestContextImpl.
        readCompleted(ZAioTCPReadRequestContextImpl.java:750)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPConnLink.
        readCompleted(ZAioTCPConnLink.java:1206)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPChannel.
        readCompleted(ZAioTCPChannel.java:929)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPChannelCPPUtilities.
        readCompleted(ZAioTCPChannelCPPUtilities.java:181)
    KEYWORDS: CLOSWAIT CLOSE_WAIT CLOS_WAIT socket sockets
    connection
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server V8.0 and V8.5                        *
    ****************************************************************
    * PROBLEM DESCRIPTION: A java.lang.NullPointerException can    *
    *                      occur in a WebSphere Application        *
    *                      Server for z/OS Controller when         *
    *                      asynchronous I/O operations complete    *
    *                      at the same time the connection is      *
    *                      being destroyed.                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The following java.lang.NullPointerException is observed in a
    WebSphere Application Server for z/OS Controller:
    SourceId:com.ibm.ws.tcp.channel.ZAioTCPChannel ProbeId:300
    java.lang.NullPointerException
    at com.ibm.ws.tcp.channel.impl.ZAioTCPConnLink.readCompleted
    (ZAioTCPConnLink.java:1197)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPChannel.readCompleted
    (ZAioTCPChannel.java:929)
    at com.ibm.ws.tcp.channel.impl.ZAioTCPChannelCPPUtilities.
    readCompleted(ZAioTCPChannelCPPUtilities.java:181)
    This problem occurs because an outstanding asynchronous I/O
    operation (which can be a read or a write) is attempting to
    complete at the same time that some other thread in the
    server is attempting to destroy the connection.  A timing
    window
    exists such that the destruction of the connection sets a field
    to null and the field is then dereferenced by the I/O
    completion.
    

Problem conclusion

  • Synchronization was added so that I/O completions that are
    currently being processed are allowed to complete before a
    connection can be destroyed.
    
    APAR PM74747 is currently targeted for inclusion in WebSphere
    Application Server V8.0 Fix Pack 8.0.0.7 and a Fix Pack 8.5.5
    of WebSphere Application Server V8.5.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM74747

  • Reported component name

    WEBSPHERE FOR Z

  • Reported component ID

    5655I3500

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-10-10

  • Closed date

    2013-03-13

  • Last modified date

    2013-05-02

  • 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

    WEBSPHERE FOR Z

  • Fixed component ID

    5655I3500

Applicable component levels

  • R800 PSY

       UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SS7K4U","label":"WebSphere Application Server for z\/OS"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"800","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
29 October 2021