From Websphere 6.1.35 to Websphere 8.5.5.17 - application startup impacted by filesystem scan - performance

Question

This is an old application and we have trouble to have the application changed.
During the deploy of a CRM like application, migrated from a 6.1.35 environment to a 8.5.5.17 websphere application server environment, the startup time of the application changed from 10 seconds to 12 minutes.
We made sono troubleshooting and we found that the problem is a remote filesystem which has 1.200.000 files. This remote filesystem is "mounted" in a path that is part of the WAR cell. This is done after the deploy of the application.
What make the application startup so slow is that on 8.5.5.17, all the files present in the path of the application are traversed (thus it tries to traverse the 1.200.000 file in the remote filesystem, which takes, as you may guess, 12 minutes...).
Anybody knows if this changed behaviour from WAS 6.1.x to WAS 8.5.5.x is intended?
Is there any workaround to block this?

Answer 1

WebSphere Application Server creates a list of files in the application when starting the application. It's a bit overzealous when creating the list in that it includes files that it does not need to look at during application start. For large applications, the file list can consume a lot of memory and can take a long time to generate. Since it is a Java EE application server, it should only be concerned with files in Java-EE-defined locations when starting the application. The list is not used during application run time. Therefore, the application server should only look in the directories:
/
META-INF/*
WEB-INF
WEB-INF/classes/*
WEB-INF/lib/*
APAR PH09294, included in 8.5.5.16 and 9.5.0.1, provides a way for you to limit the file list to the above locations. You can specify a setting either in the application or in the application server. (If you are using a version prior to 8.5.5.16 or 9.5.0.1, you should look at PM37942, which is a bit more cumbersome but still works.)
To enable the setting in the application, add the following to the MANIFEST.MF of either the EAR or the WAR. (Remember when editing MANIFEST.MF, obey the formatting rules. MANIFEST.MF must end with a blank line.) Adding the setting to a WAR limits the file list for just that WAR. Adding the setting to an EAR limits the file list for all WARs in that EAR.
IBM-Enable-File-List-Include-Filter: true
You can apply the setting to the server by setting a JVM custom property.
The following JVM custom property applies the setting to all applications on the server:
Property: org.eclipse.jst.j2ee.commonarchivecore.EnableFilesListIncludeFilter
Value: true
You can also apply the setting to all servers in a profile by adding the following line to the <WAS_PROFILE_HOME>/properties/amm.filter.properties file:
IBM-Enable-File-List-Include-Filter = true
Finally, to apply the setting to all profiles, add the above line to the <WAS_HOME>/properties/amm.filter.properties
Where should you set it? If you set it in the application, then wherever you deploy the application, the file list will be limited in scope. You do not depend on any setting in the application server. So for any large application, a developer should always include the setting in the application. An administrator might consider applying the setting to the entire WebSphere Application Server installation.