from small one page howto to huge articles all in one place
 

search text in:





Poll
Which linux distribution do you use?







poll results

Last additions:
using iotop to find disk usage hogs

using iotop to find disk usage hogs

words:

887

views:

111116

userrating:

average rating: 1.7 (85 votes) (1=very good 6=terrible)


May 25th. 2007:
Words

486

Views

224998

why adblockers are bad


Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

Workaround and fixes for the current Core Dump Handling vulnerability affected kernels

words:

161

views:

105226

userrating:

average rating: 1.3 (28 votes) (1=very good 6=terrible)


April, 26th. 2006:

Druckversion
You are here: manpages





jhat

Section: Troubleshooting Tools (1)
Updated: 21 November 2013
Index Return to Main Contents

 

NAME

jhat - Analyzes the Java heap. This command is experimental and unsupported.  

SYNOPSIS


jhat [ options ] heap-dump-file 

options
The command-line options. See Options.
heap-dump-file
Java binary heap dump file to be browsed. For a dump file that contains multiple heap dumps, you can specify which dump in the file by appending #<number> to the file name, for example, myfile.hprof#3.
 

DESCRIPTION

The jhat command parses a Java heap dump file and starts a web server. The jhat command lets you to browse heap dumps with your favorite web browser. The jhat command supports predesigned queries such as show all instances of a known class MyClass, and Object Query Language (OQL). OQL is similar to SQL, except for querying heap dumps. Help on OQL is available from the OQL help page shown by the jhat command. With the default port, OQL help is available at http://localhost:7000/oqlhelp/

There are several ways to generate a Java heap dump:

*
Use the jmap -dump option to obtain a heap dump at runtime. See jmap(1).
*
Use the jconsole option to obtain a heap dump through HotSpotDiagnosticMXBean at runtime. See jconsole(1) and the HotSpotDiagnosticMXBean interface description at http://docs.oracle.com/javase/8/docs/jre/api/management/extension/com/sun/management/HotSpotDiagnosticMXBean.html
*
Heap dump is generated when an OutOfMemoryError is thrown by specifying the -XX:+HeapDumpOnOutOfMemoryError Java Virtual Machine (JVM) option.
*
Use the hprof command. See the HPROF: A Heap/CPU Profiling Tool at http://docs.oracle.com/javase/8/docs/technotes/samples/hprof.html
 

OPTIONS

-stack false|true

Turns off tracking object allocation call stack. If allocation site information is not available in the heap dump, then you have to set this flag to false. The default is true.
-refs false|true

Turns off tracking of references to objects. Default is true. By default, back pointers, which are objects that point to a specified object such as referrers or incoming references, are calculated for all objects in the heap.
-port port-number

Sets the port for the jhat HTTP server. Default is 7000.
-exclude exclude-file

Specifies a file that lists data members that should be excluded from the reachable objects query. For example, if the file lists java.lang.String.value, then, then whenever the list of objects that are reachable from a specific object o are calculated, reference paths that involve java.lang.String.value field are not considered.
-baseline exclude-file

Specifies a baseline heap dump. Objects in both heap dumps with the same object ID are marked as not being new. Other objects are marked as new. This is useful for comparing two different heap dumps.
-debug int

Sets the debug level for this tool. A level of 0 means no debug output. Set higher values for more verbose modes.
-version

Reports the release number and exits
-h

Dsiplays a help message and exits.
-help

Displays a help message and exits.
-Jflag

Passes flag to the Java Virtual Machine on which the jhat command is running. For example, -J-Xmx512m to use a maximum heap size of 512 MB.
 

SEE ALSO

*
jmap(1)
*
jconsole(1)
*
HPROF: A Heap/CPU Profiling Tool at http://docs.oracle.com/javase/8/docs/technotes/samples/hprof.html


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO


Please read "Why adblockers are bad".



Other free services
toURL.org
Shorten long
URLs to short
links like
http://tourl.org/2
tourl.org
.
Reverse DNS lookup
Find out which hostname(s)
resolve to a
given IP or other hostnames for the server
www.reversednslookup.org
rdf newsfeed | rss newsfeed | Atom newsfeed
- Powered by LeopardCMS - Running on Gentoo -
Copyright 2004-2017 Sascha Nitsch Unternehmensberatung UG(haftungsbeschränkt)
Valid XHTML1.1 : Valid CSS : buttonmaker
- Level Triple-A Conformance to Web Content Accessibility Guidelines 1.0 -
- Copyright and legal notices -
Time to create this page: 2.5 ms