I understand that jmap is used to create heap dumps and the same can be analysed by Jhat.
jVisualVM also can be used to analyze the heap dumps (and can do much more tasks such as profiling etc).
But what is the difference between analyzing heap dumps using jHat and visualVM (other than one if using Web and second is desktop). What Sun is providing different tools and which one is better?
PS: I have limited understanding of these tools as I have worked on limited profiling/analysis tools such as JProbe, Java Heap Dump Analyzer, etc. Please correct if my understanding is wrong somewhere.
jmap and jhat are the core tools with command line interface. VisualVM is a visual workbench integrating command line tools to manage things more easily without having to work through the command line options. If you know and free comfortable working with command line tools then go with them. VisualVM doesnt do anything extra but provides a good visual interface for a better user experience. I believe it internally uses jmap/jhat.
The difference is analogous to the difference between a graphical debugger and a commandline debugger. It is often easier to work in a visual mode.
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I've managed to get a memory 'leak' in a java application I'm developing. When running my JUnit test suite I randomly get out of memory exceptions (java.lang.OutOfMemoryError).
What tools can I use to examine the heap of my java application to see what's using up all my heap so that I can work out what's keeping references to objects which should be able to be garbage collected.
VisualVM is included in the most recent releases of Java. You can use this to create a heap dump, and look at the objects in it.
Alternatively, you can also create a heapdump commandine using jmap (in your jdk/bin dir):
jmap -dump:format=b,file=heap.bin <pid>
You can even use this to get a quick histogram of all objects
jmap -histo <pid>
I can recommend Eclipse Memory Analyzer (http://eclipse.org/mat) for advanced analysis of heap dumps. It lets you find out exactly why a certain object or set of objects is alive. Here's a blog entry showing you what Memory Analyzer can do: http://dev.eclipse.org/blogs/memoryanalyzer/2008/05/27/automated-heap-dump-analysis-finding-memory-leaks-with-one-click/
If you need something free, try VisualVM
From the project's description:
VisualVM is a visual tool integrating commandline JDK tools and lightweight profiling capabilities. Designed for both development and production time use.
This is a pretty old question. A lot of people might have started using IntelliJ since it was originally answered. IntelliJ has a plugin that can show memory usage called JVM Debugger Memory View.
Use the Eclipse Memory Analyzer
There's no other tool that I'm aware of any tool that comes close to it's functionality and performance and price (free and open source) when analysing heap dumps.
Use a profiler like JProfiler or YourKitProfiler
JProfiler worked very well for me....
http://www.ej-technologies.com/products/jprofiler/overview.html
If you're using a system which supports GTK you could try using JMP.
You can try the Memory Leak Detector that is part of the JRockit Mission Control tools suite. It allows you to inspect the heap while the JVM is running. You don't need to take snapshots all the time. You can just connect online to the JVM and then see how the heap changes between garbage collections. You can also inspect objects, follow references graphically and get stack traces from where your application is currently allocating objects. Here is a brief introduction.
The tool is free to use for development and you can download it here.
I have Java application, which, unfortunately, begins to consume quite big amounts of memory after some time. To complicate things, it's not only Java application, it is also JavaFX 2 application.
I suspect that there is some memory leak, maybe even in underlying JavaFX calls and native libs.
The ideal solution would be to get a dump of all java objects at some moment (with their memory usage), and then analyze that dump. Is there some way to achieve this?
Use jmap -heap:format=b <process-id> to create a binary dump of the heap which can then be loaded into several tools - my favorite being the "Eclipse Memory Analyzer"
There are lots of ways to get a heap dump, starting with simple tools like jmap to more fancy stuff like JVisualVM or even commerical tools as JProfiler. Correctly interpreting those dumps can be tricky though, so you might want to post exactly what you are looking for. Are going hunting for a memory leak, or are you interested in getting a general feel for your application?
You can use jvisualvm. It has plugin to see live memory and get a dump out of it.
I just re-discovered this article (archive.org archive) when researching ways to grab "JVM state right at this moment" - after a heap I pulled with jmap was about half the size of what the MBeans reported. I'll add it for completeness:
su $JVM_OWNER -c "gcore -o /tmp/jvm.core $YOUR_JVM_PID"
su $JVM_OWNER -c "jmap -dump:format=b,file=jvm.hprof /usr/bin/java /tmp/jvm.core"
Requires gdb installed (for gcore) and a JDK installation (for jmap). Also note you'd might need to adjust /usr/bin/java to the path of the JVM used for the process.
I am currently using Visual VM to monitor the heap memory usage of my Java application. However I would like to somehow see the heap memory usage over a span of time like for example a day and not just get a snapshot.I would like to be able to leave Visual VM or a tool on and let it log the memory usage and then later after one day, I can go back and see a graph of it. Is there a way to do this using Visual VM? If yes, how? If not, what tool can I used to do this?
Run your Java program with the following Java options:
-Xloggc:log.out -XX:+PrintGCDetails -XX:+PrintGCTimeStamps
and download HPjmeter to visualize log.out.
Also see SUN's GC portal webpage for more options to run with. Since the data is written to a file, you won't have any problems collecting days or weeks worth of data. Of course, if you wish to visualize data with lots of information, you'll need to run HPjmeter with more memory.
Your other option is to use JConsole.
Try the Memory tab in JConsole. JConsole is also included with the Oracle JDK, like JVisualVM, so you should already have it. It has a time range of "all" which should work for what you want to do. It will look like this:
i have a socket server written in java, and i believe there is a memory leak. The i could not find anything in Netbeans' profiler, so i want to test it when it in deployed on my ubuntu server. How do i do this? What is an easy to install and use java profiler for ubuntu?
You can check out jprofiler. This works great.
http://www.ej-technologies.com/download/jprofiler/files.html
Try Java VisualVM:
sudo apt-get install visualvm
jvisualvm
First of all, if you couldn't find anything with the NetBeans profiler, then VisualVM won't give you much more satisfaction as VisualVM is a standalone version of NetBeans profiler.
That being said, my recommendation to hunt memory leaks would be Eclipse Memory Analyzer (MAT). In my opinion, this is simply the best Java heap analyzer you can get (even for money).
See also
Heap Dump Analysis with Memory Analyzer, Part 1: Heap Dumps
Heap Dump Analysis with Memory Analyzer, Part 2: Shallow Size
Automated Heap Dump Analysis: Finding Memory Leaks with One Click
Memory Analyzer Webinar
Getting Started
If you're strictly looking for a CPU and Memory profiler, famous commercial products include YourKit and JProfiler, YourKit being my preferred one (JXInsight is another excellent product but not strictly a profiler).
Related questions
Please recommend a Java profiler
What advantages have a commercial Java profiler over the free ones, e.g. the one in Netbeans?
Open Source Java Profilers
Eclipse Java Profiler
Which Java profiler is better: JProfiler or YourKit?
My multithreaded Java program crashes because it runs out of heap space and I don't think it should. Assuming the culprit is unintentional object retention, what's a good free tool to investigate what objects are being unintentionally retained?
My IDE is Eclipse.
Here's a list of open source tools you can look at: http://java-source.net/open-source/profilers . Of course, JMap and JConsole are also possible solutions.
A tool like Eclipse MAT will help to find greedy memory pigs and has even a memory leak detector.
The memory profiler of Visual VM might also help if you need to go at a lower level.
The last time I looked into free profilers, they weren't nearly as good as the established commercial ones.
I recommend evaluating
JProfiler
YourKit
JProbeand investing the money for a license of the tool you like best.
A good profiler, compared to a bad one, can easily save you a day of debugging work immediately and that pays for the license (and for the people doing the great job developing these nice tools).
All three plug into Eclipse and allow you to start profiling directly from Eclipse, from your current project, so there is no tedious work to set up the CLASSPATH.
Sun's VisualVM is free, but I am a big fan of JProfiler which is a commercial app, although you can get a 30 day trial.
I would start with tools that come with JDK, jconsole and jmap. There is good article about JVM monitoring on java.sun.com.