This section describes the Java heap analysis tool 'jhat' command and its options. 'jhat' can be used browse a Java heap dump file through a Web interface.
"jhat" - Java heap analysis tool or heap dump file browser:
Parses a Java heap dump file and launches a Web server. "jhat" enables you to browse heap dump files
using your favorite webbrowser. "jhat" supports pre-designed queries
(such as 'show all instances of a known class "Foo"') as well as OQL (Object Query Language)
- a SQL-like query language to query heap dumps.
Help on OQL is available from the OQL help page shown by "jhat".
With the default port, OQL help is available at http://localhost:7000/oqlhelp/
But the "jmap" tool included in the Windows version of JDK 1.6 only supports functions
to print histogram of Java object heap and generate a heap dump of a given JVM process:
C:\herong>\Progra~1\java\jdk1.6.0_02\bin\jhat -help
Usage: jhat [-stack <bool>] [-refs <bool>] [-port <port>]
[-baseline <file>] [-debug <int>] [-version] [-h|-help] <file>
-stack false Turn off tracking object allocation call stack.
-refs false Turn off tracking of references to objects
-port <port> Set the port for the HTTP server. Default is 7000.
-exclude <file> Specify a file that lists data members that should
be excluded from the reachableFrom query.
-baseline <file> Specify a baseline object dump. Objects in
both heap dumps with the same ID and same class
will be marked as not being "new".
-debug <int> Set debug level.
0: No debug output
1: Debug hprof file parsing
2: Debug hprof file parsing, no server
-version Report version number
-h|-help Print this help and exit
<file> The file to read
For a dump file that contains multiple heap dumps,
you may specify which dump in the file
by appending "#<number>" to the file name, i.e. "foo.hprof#3".
All boolean options default to "true"
