*Problem Statement*
Memory leak in web application running on Tomcat
*System Information*
Tomcat 5.5.27
Apache HTTPD 2.2.9
Java HotSpot(TM) Server VM (build 1.5.0_14-b03, mixed mode)
Mod_proxy_http connector
Solaris 10 x86
Tomcat JVM heap settings: min:2GB and max:2GB
*Observations and Investigation Done*
Under load, the web application slowly runs out of heap space. The heap
utilization graph suggests a memory leak type pattern.
Heap dumps were gathered to determine the root cause and observations are as
below from the dumps:
1. HashMap entries from the below object reference tree seem to consume
over 80% of the used tenured generation space.
org/apache/jasper/compiler/JspRuntimeContext
↓
Java/util/Collections$SynchronizedMap
↓
Java/util/HashMap
↓
Java/util/HashMap$Entry
1. Heap dumps gathered during different times and after a Full GC always
indicate 100 entries
2. The number of objects referenced by each HashMap entry vary between
2-3
1. These are either a String and JspServletWrapper object
or
1. A String, JspServletWrapper and *another HashMap Entry*. This call
reference tree of HashMap entries referenced by another HashMap entry can
repeat to a depth of approximately 8-10 nodes
The above is indicated in an object reference tree obtained after analyzing
the Heap dump as shown below
1. The maximum percentage of the memory occupied by the HashMap entry
object is by a character array that seems like the JSP servlet response.
HTML response (tags with content) can be seen in the character array
*Questions*
1. I am stuck at this point and have run out of ideas on how to get to
the root cause of this issue. Do you have any ideas/suggestions to help
identify the root cause?
2. I google and found the following interesting links
1. http://www.mail-archive.com/[email protected]/msg03395.html Is
there any know issues, configuration that causes a memory leak
by caching of
servlet responses in the container and not flushing the cached objects?
2.
http://mail-archives.apache.org/mod_mbox/tomcat-users/200303.mbox/%3c000c01c2ee2c$41c079a0$03b69...@garethdqw0t9if%3ewe
use a lot of JSTL in our web application. Are there any known issues
around memory issues as indicated on the link?
Any inputs to help identify the root cause of this problem would be highly
appreciated.
Kind Regards
Anurag
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Anurag Kapur
Senior Associate - Technology,
Sapient Corporation.
http://www.linkedin.com/in/anuragkapur
http://www.google.com/profiles/anuragkapur
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