Generating Heap Dump File with 'jmap'

This section provides a tutorial example on how to generate a heap dump file with the 'jmap -dump:file=name' command. A heap dump file contains all heap objects of JVM process.

The second function of the "jmap" tool is to generate a heap dump of a given JVM process with the "jmap -dump:file=<filename>" command:

   -Xms24m -Xmx24m GarbageCollection

Free/total memory:
23725256   25034752
22710400   25034752
21618728   25034752
20523584   25034752

(Start another command window.)
C:\herong>\Progra~1\java\jdk1.8.0\bin\jps -l -m

764 GarbageCollection
1204 -l -m

C:\herong>\Progra~1\java\jdk1.8.0\bin\jmap 764

Dumping heap to C:\herong\ ...
Heap dump file created

C:\herong>dir *.map

  12:08 AM        19,816,895

So the heap dump file, "", is a snapshot of all heap objects used by the running process.

Heap dump files can be browsed by the heap dump browser, "jhat", as described in the next section.

Last update: 2015.

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

 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

 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

 Outdated Tutorials


 PDF Printing Version