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PK72336; NullPointerException from channel frame work after PK63328

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Abstract

WebContainer threads hang and/or missing response data resulting from a forwarded request.

Download Description

PK72336 resolves the following problem:

ERROR DESCRIPTION:
WebContainer threads hang and/or missing response data resulting from a forwarded request. For example:

WebContainer threads become unusable after the following exception is logged.

java.lang.NullPointerException
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:111)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473)

LOCAL FIX:
Note that the problems only happen when response data is sent asynchronously. As a result it is possible to prevent the problems by forcing all response data to sent be synchronously. This can be done by setting the webcontainer custom property:

com.ibm.ws.webcontainer.channelwritetype=sync

PROBLEM SUMMARY:

USERS AFFECTED:
Users of WebSphere Application Server Version 6.1.0.19.

PROBLEM DESCRIPTION:
Various issues including hanging threads and missing response data
resulting from a forwarded request.

RECOMMENDATION:
None

PK63328 introduced an issue where a http connection can be closed too


early for a response from a forwarded request. Depending on the timing
of when the http connection is closed several different symptoms have
been observed and these include:

- Null pointer exceptions
- Missing response data
- Hanging threads

Other symptoms may also be possible.

Note that the problem only occurs when response data is sent asynchronously and as a result are more likely to occur under load and will not happen when the following WebContainer custom property is set:

com.ibm.ws.webcontainer.ChannelWriteType=sync


One example of a NullPointerException exception resulting from the problem is:

java.lang.NullPointerException
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:11
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java
95)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(Resu
Handler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:87
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473

Another example of a NullPointerException exception resulting from the problem is:

java.lang.NullPointerException
at com.ibm.ws.tcp.channel.impl.NioSocketIOChannel.
attemptWriteToSocketUsingNIO(NioSocketIOChannel.java:158)
at com.ibm.ws.tcp.channel.impl.SocketIOChannel.
attemptWriteToSocket(SocketIOChannel.java:744)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO
(WorkQueueManager.java:628)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun
(WorkQueueManager.java:979)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run
(WorkQueueManager.java:1064)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1462


PROBLEM CONCLUSION:
The WebContainer has been updated to only close a connection
after the sending of the response data from forward request is
complete.


The fix for this APAR is currently targeted for inclusion in fixpacks 6.1.0.21. and 7.0.0.1.

Please refer to the Recommended Updates page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Prerequisites

Please download the UpdateInstaller below to install this fix.

[{"PRLabel":"UpdateInstaller","PRLang":"US English","PRSize":"7250000","PRPlat":{"label":"AIX","code":"PF002"},"PRURL":"http://www.ibm.com/support/docview.wss?rs=180&uid=swg21205991"}]

Installation Instructions

Please review the readme.txt for detailed installation instructions.

[{"INLabel":"Readme","INLang":"US English","INSize":"8739","INURL":"ftp://public.dhe.ibm.com/software/websphere/appserv/support/fixes/PK72336/readme.txt"}]

Download Package

Download package
What is Fix Central (FC)?
What is DD?

Download RELEASE DATE LANGUAGE SIZE(Bytes) Download Options
6.1.0.19-WS-WAS-IFPK7233610-10-2008US English11919FCFTPDD

On
[{"DNLabel":"6.1.0.19-WS-WAS-IFPK72336","DNDate":"10-10-2008","DNLang":"US English","DNSize":"11919","DNPlat":{"label":"AIX","code":"PF002"},"DNURL":null,"DNURL_FTP":null,"DDURL":null}]

Technical Support

Contact IBM Support using SR (http://www-306.ibm.com/software/support/probsub.html), visit the WebSphere Application Server Support Web site (http://www.ibm.com/software/webservers/appserv/was/support/), or contact 1-800-IBM-SERV(U.S. only).

[{"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Business Unit":{"code":"BU004","label":"Hybrid Cloud"},"Component":"Servlet Engine\/Web Container","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF012","label":"IBM i"},{"code":"PF016","label":"Linux"}],"Version":"6.1.0.19","Edition":"Base;Network Deployment"}]

Document Information

Modified date:
15 June 2018

UID

swg24020800