PM07309; 7.0.0.9: Performance and memory problems caused by redundant loads

Download Description

PM07309 resolves the following problem:

ERROR DESCRIPTION:
During the close of internal application objects, the close steps force a redundant load of application metadata as a part of a step that is clearing metadata from memory. Since the objective is to remove the metadata from memory, performing a load during the close is redundant, and is leading to extra processing time, as well as delaying the release of application objects.

LOCAL FIX:
n/a

PROBLEM SUMMARY:

USERS AFFECTED:
All users of IBM WebSphere Application Server.

PROBLEM DESCRIPTION:
Excess memory utilization caused by redundant loads of application metadata.

RECOMMENDATION:
None

Code which performs shutdowns of application modules could cause a redundant reload of application metadata.

The problem does not cause a memory leak, but does cause memory usage to be higher than necessary, and does cause allocations to be retained longer than necessary.

The problem is demonstrated by a Java stacktrace showing calls from DeployedModuleImpl$DMIAlarm.alarm through DeployedModuleImpl.close and leading eventually to code within the XML parsing layer. For example:

org/apache/xerces/jaxp/DocumentBuilderImpl.parse(Bytecode
PC:57(CompiledCode))
4XESTACKTRACE at
javax/xml/parsers/DocumentBuilder.parse(Bytecode
PC:25(Compiled Code))
4XESTACKTRACE at
com/ibm/ejs/models/base/extensions/helper/CommonExtensionsHelper
.getInputStream(CommonExtensionsHelper.java:138(Compiled Code))
4XESTACKTRACE at
com/ibm/ejs/models/base/extensions/helper/CommonExtensionsHelper
.isMetadataComplete(CommonExtensionsHelper.java:94(Compiled
Code))
4XESTACKTRACE at
com/ibm/ejs/models/base/extensions/ejbext/EjbExtensionsHelper.is
MetadataComplete(EjbExtensionsHelper.java:236(Compiled Code))
4XESTACKTRACE at
com/ibm/etools/commonarchive/impl/EJBJarFileImpl.isAnnotationsSu
pported(EJBJarFileImpl.java:584(Compiled Code))
4XESTACKTRACE at
org/eclipse/jst/j2ee/commonarchivecore/internal/impl/EJBJarFileI
mpl.getDeploymentDescriptor(EJBJarFileImpl.java:307(Compiled
Code))
4XESTACKTRACE at
org/eclipse/jst/j2ee/commonarchivecore/internal/impl/EJBJarFileI
mpl.getStandardDeploymentDescriptor(EJBJarFileImpl.java:429(Comp
iled Code))
4XESTACKTRACE at
org/eclipse/jst/j2ee/commonarchivecore/internal/impl/EARFileImpl
.getDeploymentDescriptor(EARFileImpl.java:466(Compiled Code))
4XESTACKTRACE at
org/eclipse/jst/j2ee/commonarchivecore/internal/impl/EARFileImpl
.getDeploymentDescriptor(EARFileImpl.java:447(Compiled Code))
4XESTACKTRACE at
org/eclipse/jst/j2ee/commonarchivecore/internal/impl/ModuleRefIm
pl.getDeploymentDescriptor(ModuleRefImpl.java:202(Compiled
Code))
4XESTACKTRACE at
com/ibm/ws/runtime/component/DeployedModuleImpl.getDeploymentDes
criptor(DeployedModuleImpl.java:366(Compiled Code))
4XESTACKTRACE at
com/ibm/ws/runtime/component/DeployedModuleImpl.close(DeployedMo
duleImpl.java:305(Compiled Code))
4XESTACKTRACE at
com/ibm/ws/runtime/component/DeployedModuleImpl$DMIAlarm.alarm(D
eployedModuleImpl.java:805)

PROBLEM CONCLUSION:
A code change was made to avoid loading the application metadata during the close operation.

The fix for this APAR is currently targeted for inclusion in fix pack 7.0.0.13. Refer to the Recommended Updates page for delivery information:
http://www.ibm.com/support/docview.wss?uid=swg27004980