Well purpose of writing this page on JVM & JVM
monitoring / Tuning for Oracle Apps 11i is that for Quite some time we
were getting errors like java.lang.OutOfMemoryError or
java.lang.NoClassDefFoundError error message across
applications. So I thought of troubleshooting JVM and Middle Tier in
Oracle Applications 11i and got enough material which I have
summarized here for other as well. This page is based on Oracle
Application 11i with Autoconfig and Java 1.4.2 version. Though
Java/JDK 1.5 is also available & certified with 188.8.131.52 . Lets
start with understanding JVM (Java Virtual Machine) and related
What is JVM ?
JVM acronym for Java Virtual Machine which executes instructions
generated by Java compiler. So user click on any Self Service Request or
any program which uses Java, then Apache forwards this request to
mod_jserv (mod_oc4j in 10g AS) & mod_jserv caters this request with
help of JVM.
How & Where check JVM related configuration in
Oracle Apps 11i ?
So lets start with CONTEXT file under $APPL_TOP/admin (xml file)
which is of pattern $SID_$HOSTNAME.xml
There are two important lines
in CONTEXT file which will help you in understanding JVM
jvm_options oa_var="s_jvm_options" osd="Solaris" -verbose:gc
-Xmx512M -Xms128M -XX:MaxPermSize=128M -XX:NewRatio=2
-XX:+PrintGCTimeStamps -XX:+UseTLAB /jvm_options
means JVM is configured to print output when gc(Garbage Collector) runs.
Xmx is maximum memory allocated to JVM in above example its 512 MB.
Xms is JVM will start with this much memory i.e. 128 MB.
Now Check another line in 11i Context file like
means that there are two JVM's for OACore Group. Usually default its 1
JVM in my Instance I changed it to 2, to cater huge Self Service users
in my case.
To Check further how to increase number of JVM's, Types
of group , Monitoring & Tuning Apps 11i JVM, Click Next