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Performance issue with tomcat 5.x.x series R

August 6th, 2007

one of our escenic colleagues (Simen L. Haagenrud) just noticed a bottleneck with tomcat 5.x.x series containers. so we had a details digging to let find the reason.

as he mentioned it was because of recurring invocation of “getAttribute”, and tomcat 5.x.x series is using synchornization block inside “getAttribute” method, where lock is kept on “attributes” variable.
so i had a quick look on the source code of the 3 recent series -

1. 5.0.28
http://svn.apache.org/repos/asf/tomcat/container/tags/tc5.0.x/TOMCAT_5_0_28/catalina/src/share/org/apache/catalina/core/ApplicationContext.java

2. 5.5.24 (the last version from 5.5.x series)
http://svn.apache.org/repos/asf/tomcat/container/tags/tc5.5.x/TOMCAT_5_5_24/catalina/src/share/org/apache/catalina/core/ApplicationContext.java

3. 6.0.x (trunk)
http://svn.apache.org/repos/asf/tomcat/tc6.0.x/trunk/java/org/apache/catalina/core/ApplicationContext.java

so the code says 6.0.x series came with the fixes, the fix is the replacement of HashMap with ConcurrentHashMap.

in his case, recurring invocation of “getAttribute” was nearly reduced 50% server request handling capability.
best wishes,

Posted in Java, java ee, server, Fix, tomcat
Comments(1)

Firefox 1.5 with ajax sync request. R

April 26th, 2007

This post is to remind myself about a bug on Firefox 1.5.

bug details:

Http ajax request doesn’t invoke “onstatechange” handler if ajax request type is set to sync.

how to resolve this problem:

invoke “onstatechange” function manually.

Posted in Introduction, bug, Fix, remind, firefox
Comments(1)

RSSOwl on Ubuntu (mozilla browser component) R

October 26th, 2006

RSSOwl is my favorite RSS feed reader, recently i have setup mozilla browser component. here is simple extention for run.sh ( it could be found under %RSSOWL_DIR%/run.bat ).

#!/bin/sh
export MOZILLA_FIVE_HOME=’/usr/lib/mozilla-firefox/’
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$MOZILLA_FIVE_HOME
java -Xmx96m -Djava.library.path=$RSSOWL_DIR -jar $RSSOWL_DIR/rssowl.jar

thats’s it. now open RSS Owl, now it will display feed content using Mozilla browser component…

Posted in Fix
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Every time I try to access my repository, the process just hangs R

October 19th, 2006

one of our repositories was hanging while user was trying to checkout. to resolve this problem i found the following lines from svn FAQ. Now it has been fixed.

Your repository is not corrupt, nor is your data lost. If your process accesses the repository directly (mod_dav_svn, svnlook, svnadmin, or if you access a `file://’ URL), then it’s using Berkeley DB to access your data. Berkeley DB is a journaling system, meaning that it logs everything it is about to do before it does so. If your process is interrupted (Control-C, or segfault), then a lockfile is left behind, along with a logfile describing unfinished business. Any other process that attempts to access the database will just hang, waiting for the lockfile to disappear. To awaken your repository, you need to ask Berkeley DB to either finish the work, or rewind the database to a previous state that is known to be consistent.

collected from - http://subversion.tigris.org/faq.html#bdb-recovery
just apply “svnadmin recover /path/to/your/repository”

Posted in Fix
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