JVM Troubleshooting Tools
This chapter tutorial notes on JVM troubleshooting tools. Topics include 'jinfo' to check JVM option values, 'jstack' to dump stack traces and detect deadlocks, 'jmap' to print heap histogram and dump heap files, 'jhat' to browse head files and run OQL queries.
JVM Troubleshooting Tools in JDK 1.5
'jinfo' - VM Option Value Checker
Changing HotSpot VM Option using 'jinfo'
'jstack' - Stack Tracer to Generate Thread Dump
What Is a Thread Dump?
Java Thread Deadlock Demo Program
Detecting Java Thread Deadlocks with 'jstack'
'jmap' - JVM Heap Dump Tool
Printing Histogram of Java Object Heap
Generating Heap Dump File with 'jmap'
'jhat' - Java Heap Analysis Tool
Starting 'jhat' Web Server on a Heap Dump File
Listing Instance Counts of All Classes
Browsing Object Instance Values
Object Query Language (OQL)
Searching for Instances with OQL Statements
- JDK offers a number of nice trouble shooting tools: jinfo, jstack, jmap, and jhat.
- jinfo allows you to check current JVM options of a running JVM process.
- jstack allows you to generate a thread dump (print all threads and their stack traces) of a JVM process. It can also be used to detect deadlocks.
- A thread dump is a snapshot of all threads that are currently in a JVM process at a given moment.
It also includes the state and stack trace of each thread.
- jmap allows you to generate a heap dump of a JVM process.
It can also be used to print memory usages and instance counts by classes.
- A heap dump is a snapshot of all data objects that are currently in a JVM process at a given moment.
- jhat allows you to browse a heap dump file with a Web interface.
- jhat also supports OQL (Object Query Language) statements - a very powerful tool to investigate
any data issues in your Java application.
Table of Contents
About This Book
Java Tools Terminology
Installing Java 8 on Windows
'javac' - The Java Program Compiler
'java' - The Java Program Launcher
'jdb' - The Java Debugger
'jconsole' - Java Monitoring and Management Console
'jstat' - JVM Statistics Monitoring Tool
►JVM Troubleshooting Tools
jvisualvm (Java VisualVM) - JVM Visual Tool
'jar' - The JAR File Tool
'javap' - The Java Class File Disassembler
'keytool' - Public Key Certificate Tool
'native2ascii' - Native-to-ASCII Encoding Converter
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