JSP Cache Issues in 11i and R12
Mar 4, 2009 / By Vasu Balla
As an Apps DBA, you might have been asked to clear the JSP cache many times, either by Developers or Oracle Support. The usual directory that holds the JSP cache is
$COMMON_TOP/_pages in 11i and R12 releases. In older versions of 11i it used to be
What is this JSP Cache? It’s the compiled version of JSP files. When JSP gets compiled by Apache Jserv, it gets internally gets converted into a .java file (servlet) and then that .java file gets compiled into a .class file
Why do we need to clear the JSP cache? To optimize JSP runtime performance. Even if after you update a JSP file in
$OA_HTML directory, Jserv will only look for .class files in the
_pages directory. If it doesn’t find the .class file, then it attempts to compile the .jsp into a .class file and then run it. In R12, this behavior changed a bit, as JSP are being handled by OC4J instead of Jserv. In R12, if OC4J doesn’t find the .class file in the
_pages directory, it will just render a blank page and will not even attempt to compile the JSP.
The good news is that there is a script to manually compile JSPs. The script name is
ojspCompile.pl, located in
$JTF_TOP/admin/scripts in 11i, and
$FND_TOP/patch/115/bin in R12. We can use this perl script to compile the JSPs. Note that we must bounce the Apache service in 11i, and the oacore service in R12 for changes to take effect. This is because, if the .class file is already loaded into the JVM’s memory, it will not even look under the
_pages directory for updated files. This is another optimization in Jserv and OC4J for better JSP performance.
In a Development Instance with active customizations going on, it’s a pain for the DBA to clear the JSP cache or compile JSPs manually. If you are facing this problem, don’t worry, here is a fix for this issue.
In 11i, change
developer_mode to true in the
zone.properties file in the line below:
In R12, change
recompile in the
orion-web.xml file under the
<init-param> <param-name>main_mode</param-name> <param-value>justrun</param-value> </init-param>
These parameter changes will make Jserv and OC4J look for updated JSP and class files whenever they try to get executed. These parameters are not recommended in Production, as checking file timestamps adds additional overhead to page load times, but it is definitely worth setting in a Development environment.
Another point is, in R12,
orion-web.xml changes can be made permanent by updating the
s_jsp_main_mode tag from
recompile in the context xml file.
I’d love to hear your experiences with the JSP cache, as well and how this post might have helped you.