Java Tools Tutorials - Herong's Tutorial Examples - v6.23, by Herong Yang
jmap - Generating Heap Dump File
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:
herong> java -Xmx24m GarbageCollection Free/total memory: 23725256 25034752 22710400 25034752 21618728 25034752 20523584 25034752 ... (Start another command window.) herong> jps -l -m 10672 GarbageCollection 1256 jdk.jcmd/sun.tools.jps.Jps -l -m herong> jmap -dump:file=GarbageCollection.map 10672 Heap dump file created herong> dir *.map 22,306,616 GarbageCollection.map
So the heap dump file, "GarbageCollection.map", is a snapshot of all heap objects used by the running GarbageCollection.java process. The size of the heap dump file should be the same as all currently allocated objects in the heap.
Table of Contents
javac - The Java Program Compiler
java - The Java Program Launcher
jpackage - Binary Package Builder
javadoc - The Java Document Generator
jdeps - The Java Class Dependency Analyzer
jdeprscan - The Java Deprecated API Scanner
jcmd - The JVM Diagnostic Tool
jconsole - Java Monitoring and Management Console
jstat - JVM Statistics Monitoring Tool
JVM Troubleshooting Tools in JDK
jinfo - VM Option Value Checker
jinfo - Changing HotSpot VM Option
jstack - Stack Tracer to Generate Thread Dump
Java Thread Deadlock Demo Program
jstack - Detecting Java Thread Deadlocks
Printing Histogram of Java Object Heap
►jmap - Generating Heap Dump File
jhat - Java Heap Analysis Tool
jhat - Starting Web Server on a Heap Dump File
Listing Instance Counts of All Classes
Browsing Object Instance Values
Searching for Instances with OQL Statements
jhsdb - The Java HotSpot Debugger
jvisualvm (Java VisualVM) - JVM Visual Tool
javap - The Java Class File Disassembler
keytool - Public Key Certificate Tool
jrunscript - Script Code Shell
native2ascii - Native-to-ASCII Encoding Converter