Java Tools Tutorials - Herong's Tutorial Examples - Version 6.20, by Dr. Herong Yang
jmap - JVM Heap Dump Tool
This section describes the JVM heap dump tool, 'jmap', command and its options. Windows version of 'jmap' can print heap histogram and generate heap dump.
What Is "jmap"? "jmap" (Java memory Map) is tool to print shared object memory maps or heap memory details of a given JVM process or a Java core file on the local machine or on a remote machine through a debug server.
The "jmap" tool included in the Windows version of JDK supports functions to print histogram of Java object heap and generate a heap dump of a given JVM process:
C:\herong>jmap Usage: jmap -clstats <pid> to connect to running process and print class loader statistics jmap -finalizerinfo <pid> to connect to running process and print information on objects awaiting finalization jmap -histo[:live] <pid> to connect to running process and print histogram of java object heap if the "live" suboption is specified, only count live objects jmap -dump:<dump-options> <pid> to connect to running process and dump java heap dump-options: live dump only live objects; if not specified, all objects in the heap are dumped. format=b binary format file=<file> dump heap to <file> Example: jmap -dump:live,format=b,file=heap.bin <pid>
See the next section on how to use "jmap" to print heap histogram and to generate heap dump.
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