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Stack Traces andThread Dumps
A stack trace is a user-friendly snapshot of the threads and monitors in a Virtual Machine for
the Java platform (Java Virtual Machine or JVM machine). A thread dump shows what every
thread in a JVM is doing at a given time and is useful in debugging. When the application server
freezes, hangs, or becomes sluggish for no apparent reason, you should generate and analyze a
thread dump.
This section explains how to obtain a thread dump for Enterprise Server. More information
about analyzing the information contained in a thread dump can be found in “An Introduction
to Java Stack Traces”
(
http://java.sun.com/developer/technicalArticles/Programming/Stacktrace). By
default, the server dumps a core le and restarts with the -Xrs java-option ag in the
server.xml le.
▼
To Obtain a ServerThread Dump
Type thefollowing command:
asadmin generate-jvm-report --type=thread
generate-jvm-report(1)
VisualVM
VisualVM is a Java troubleshooting tool that uses various technologies such as jvmstat, JMX
TM
,
and Attach API to access monitored applications. VisualVM is a tool for visualizing data
sources and by default visualizes the following types: applications, hosts, snapshots, core
dumps, heap dumps, and thread dumps. These data sources are visualized in VisualVM so that
they can be monitored for the purposes of analysis, management, and troubleshooting.
VisualVM is commonly used to detect memory leaks.
VisualVM has a GlassFish plugin that enhances monitoring of hosted applications by adding
specialized overview, a tab for monitoring the HTTP Service, and the ability to visually select
and monitor any of the deployed web applications. You can experiment with VisualVM
troubleshooting capabilities, but note that various features depend on the Java versions used in
the client and server. Depending on your conguration, you might only get parts of the
VisualVM features. For more information about VisualVM, see
https://visualvm.dev.java.net.
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See Also
TroubleshootingTools
SunGlassFishEnterpriseServerv3PreludeTroubleshootingGuide • November200818