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Posted to taglibs-dev@jakarta.apache.org by bu...@apache.org on 2006/05/18 19:12:56 UTC
DO NOT REPLY [Bug 39612] New: - Sudden Nullpointerexception in LRUCache
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http://issues.apache.org/bugzilla/show_bug.cgi?id=39612
Summary: Sudden Nullpointerexception in LRUCache
Product: Taglibs
Version: 1.2.0
Platform: Other
OS/Version: Linux
Status: NEW
Severity: critical
Priority: P2
Component: Cache Taglib
AssignedTo: taglibs-dev@jakarta.apache.org
ReportedBy: silentcrooner@gmail.com
After running the Cache Taglib successfully in a JBoss 4.x.x environment for
many months, I have suddenly experienced a very nasty NullpointerException on
the frontpage of our high volume site, where the tag is used to cache dynamic
list contents in session scope.
I have not configured the tag using a CacheUtil class but using the default
parameters.
This happened for all users/sessions requesting the front page.
An immediate restart of JBoss solved the issue - but obviously this is highly
worrying.
I have scoured bugzilla and tried to Google for something similar from CacheTag
users to no avail.
Looking into the LRUCache class and comparing to my stack trace it seems that in
same strange scenario the key can be null, but still return valid entries from
the cache. A NullPointerException then occurs when trying to update the LRU list
in the noteUsed method afterwords.
18:12:53,755 ERROR [Engine] StandardWrapperValve[jsp]: Servlet.service() for ser
vlet
jsp threw exception
java.lang.NullPointerException
at java.util.LinkedList.remove(LinkedList.java:220)
at org.apache.taglibs.cache.LRUCache.noteUsed(LRUCache.java:199)
at org.apache.taglibs.cache.LRUCache.get(LRUCache.java:115)
at org.apache.taglibs.cache.CacheTag.doStartTag(CacheTag.java:49)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:528)
Could this be a threading issue or what?
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DO NOT REPLY [Bug 39612] - Sudden Nullpointerexception in LRUCache
Posted by bu...@apache.org.
DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG�
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://issues.apache.org/bugzilla/show_bug.cgi?id=39612>.
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INSERTED IN THE BUG DATABASE.
http://issues.apache.org/bugzilla/show_bug.cgi?id=39612
------- Additional Comments From kris@dotech.com 2006-05-19 14:50 -------
It certainly could be a threading/concurrency issue. I've never used the taglib
before, but I took a quick look through the code. It's a bit disturbing that
there's literally no synchronization anywhere in the taglib when it's likely
that caches are stored in shared scopes (session and application).
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