APAR status
Closed as program error.
Error description
On certain conditions, the below message is seen in logs:
java.util.ConcurrentModificationException: concurrent access to
HashMap
attempted by Thread[Servlet.Engine.Transports : 0,5,main]
at java.util.HashMap.onEntry(HashMap.java(Inlined Compiled
at java.util.HashMap.transfer(HashMap.java(Compiled Code))
at java.util.HashMap.resize(HashMap.java(Inlined Compiled
at java.util.HashMap.addEntry(HashMap.java(Compiled Code))
at java.util.HashMap.put(HashMap.java(Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebApp.setAttribute(WebApp.
Local fix Problem summary
****************************************************************
* USERS AFFECTED: WebSphere Application Server users with *
* their applications accessed by multiple *
* clients concurrently. *
****************************************************************
* PROBLEM DESCRIPTION: A ConcurrentModificationException might *
* be thrown when applications are *
* accessed by multiple users *
* simultaneously. *
****************************************************************
* RECOMMENDATION: *
****************************************************************
In the Webcontainer code there is a HashMap that was not
serialized. Therefore, if this HashMap was accessed by
multiple threads at the same time a
ConcurrentModificationException will be thrown. This behaviour
is random and difficult to reproduce, however it will
typically arise when a large amount of users are accessing the
application at the same time.
The following is the stack trace of the exception that might be
thrown:
java.util.ConcurrentModificationException: concurrent access to
HashMap attempted by Thread[Servlet.Engine.Transports: 0,5,main]
at java.util.HashMap.onEntry(HashMap.java(Inlined Compiled Code)
at java.util.HashMap.transfer(HashMap.java(Compiled Code))
at java.util.HashMap.resize(HashMap.java(Inlined Compiled Code))
at java.util.HashMap.addEntry(HashMap.java(Compiled Code))
at java.util.HashMap.put(HashMap.java(Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebApp.setAttribute
(WebApp.java:1768)
Problem conclusion
The Webcontainer code was modified so that the HashMap is now
instantiated with the following call:
Collections.synchronizedMap(new HashMap())
This synchronizes the HashMap to alleviate the possibility of
a ConcurrentModificationException occuring.
The fix for this APAR is currently targeted for inclusion in
fixpacks 5.1.1.12, 6.0.2.15, and 6.1.0.3. 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 |
PK27027 |
Reported component name |
WEBSPHERE BASE |
Reported component ID |
5630A3600 |
Reported release |
00W |
Status |
CLOSED PER |
PE |
NoPE |
HIPER |
NoHIPER |
Special Attention |
NoSpecatt |
Submitted date |
2006-06-23 |
Closed date |
2006-07-31 |
Last modified date |
2006-10-17 |
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Modules/Macros
Publications Referenced
|
Fix information |
Fixed component name |
WEBSPHERE BASE |
Fixed component ID |
5630A3600 |
Applicable component levels |
R003 PSY |
UP |
R00A PSY |
UP |
R00H PSY |
UP |
R00I PSY |
UP |
R00P PSY |
UP |
R00S PSY |
UP |
R00W PSY |
UP |
R103 PSY |
UP |
R10A PSY |
UP |
R10H PSY |
UP |
R10I PSY |
UP |
R10P PSY |
UP |
R10S PSY |
UP |
R10W PSY |
UP |
|