Is it possible to see the heap of a program in eclipse itself while it is executing? Is there a plugin for that?
I don't know if there is an Eclipse plugin, but if what matters is getting the information and not necessarily through Eclipse then you can do that with JVisualVM, and there are several plugins that provide all the details that you want.
One of its features is that you can make a heap dump.
Documentation says:
Take and browse heap dumps. When you need to browse contents of application memory or uncover a memory leak in your application,
you'll find the built-in HeapWalker tool really handy. It can read
files written in hprof format and is also able to browse heap dumps
created by the JVM on an OutOfMemoryException.
Eclipse does have a plugin called Eclipse Memory Analyzer (MAT). You can check it out here. I heard it is quite handy for heap analysis and fixing memory leaks in your program.
http://www.eclipse.org/mat/
Related
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 $JVM_OWNER -c "jmap -dump:format=b,file=jvm.hprof /usr/bin/java /tmp/jvm.core"
Requires gdb installed (for gcore) and a JDK installation (for jmap). Also note you'd might need to adjust /usr/bin/java to the path of the JVM used for the process.
I have a HotSpot JVM heap dump that I would like to analyze. The VM ran with -Xmx31g, and the heap dump file is 48 GB large.
I won't even try jhat, as it requires about five times the heap memory (that would be 240 GB in my case) and is awfully slow.
Eclipse MAT crashes with an ArrayIndexOutOfBoundsException after analyzing the heap dump for several hours.
What other tools are available for that task? A suite of command line tools would be best, consisting of one program that transforms the heap dump into efficient data structures for analysis, combined with several other tools that work on the pre-structured data.
Normally, what I use is ParseHeapDump.sh included within Eclipse Memory Analyzer and described here, and I do that onto one our more beefed up servers (download and copy over the linux .zip distro, unzip there). The shell script needs less resources than parsing the heap from the GUI, plus you can run it on your beefy server with more resources (you can allocate more resources by adding something like -vmargs -Xmx40g -XX:-UseGCOverheadLimit to the end of the last line of the script.
For instance, the last line of that file might look like this after modification
./MemoryAnalyzer -consolelog -application org.eclipse.mat.api.parse "$#" -vmargs -Xmx40g -XX:-UseGCOverheadLimit
Run it like ./path/to/ParseHeapDump.sh ../today_heap_dump/jvm.hprof
After that succeeds, it creates a number of "index" files next to the .hprof file.
After creating the indices, I try to generate reports from that and scp those reports to my local machines and try to see if I can find the culprit just by that (not just the reports, not the indices). Here's a tutorial on creating the reports.
Example report:
./ParseHeapDump.sh ../today_heap_dump/jvm.hprof org.eclipse.mat.api:suspects
Other report options:
org.eclipse.mat.api:overview and org.eclipse.mat.api:top_components
If those reports are not enough and if I need some more digging (i.e. let's say via oql), I scp the indices as well as hprof file to my local machine, and then open the heap dump (with the indices in the same directory as the heap dump) with my Eclipse MAT GUI. From there, it does not need too much memory to run.
EDIT:
I just liked to add two notes :
As far as I know, only the generation of the indices is the memory intensive part of Eclipse MAT. After you have the indices, most of your processing from Eclipse MAT would not need that much memory.
Doing this on a shell script means I can do it on a headless server (and I normally do it on a headless server as well, because they're normally the most powerful ones). And if you have a server that can generate a heap dump of that size, chances are, you have another server out there that can process that much of a heap dump as well.
First step: increase the amount of RAM you are allocating to MAT. By default it's not very much and it can't open large files.
In case of using MAT on MAC (OSX) you'll have file MemoryAnalyzer.ini file in MemoryAnalyzer.app/Contents/MacOS. It wasn't working for me to make adjustments to that file and have them "take". You can instead create a modified startup command/shell script based on content of this file and run it from that directory. In my case I wanted 20 GB heap:
./MemoryAnalyzer -vmargs -Xmx20g --XX:-UseGCOverheadLimit ... other params desired
Just run this command/script from Contents/MacOS directory via terminal, to start the GUI with more RAM available.
I suggest trying YourKit. It usually needs a little less memory than the heap dump size (it indexes it and uses that information to retrieve what you want)
The accepted answer to this related question should provide a good start for you (if you have access to the running process, generates live jmap histograms instead of heap dumps, it's very fast):
Method for finding memory leak in large Java heap dumps
Most other heap analysers (I use IBM http://www.alphaworks.ibm.com/tech/heapanalyzer) require at least a percentage of RAM more than the heap if you're expecting a nice GUI tool.
Other than that, many developers use alternative approaches, like live stack analysis to get an idea of what's going on.
Although I must question why your heaps are so large? The effect on allocation and garbage collection must be massive. I'd bet a large percentage of what's in your heap should actually be stored in a database / a persistent cache etc etc.
This person http://blog.ragozin.info/2015/02/programatic-heapdump-analysis.html
wrote a custom "heap analyzer" that just exposes a "query style" interface through the heap dump file, instead of actually loading the file into memory.
https://github.com/aragozin/heaplib
Though I don't know if "query language" is better than the eclipse OQL mentioned in the accepted answer here.
The latest snapshot build of Eclipse Memory Analyzer has a facility to randomly discard a certain percentage of objects to reduce memory consumption and allow the remaining objects to be analyzed. See Bug 563960 and the nightly snapshot build to test this facility before it is included in the next release of MAT. Update: it is now included in released version 1.11.0.
A not so well known tool - http://dr-brenschede.de/bheapsampler/ works well for large heaps. It works by sampling so it doesn't have to read the entire thing, though a bit finicky.
This is not a command line solution, however I like the tools:
Copy the heap dump to a server large enough to host it. It is very well possible that the original server can be used.
Enter the server via ssh -X to run the graphical tool remotely and use jvisualvm from the Java binary directory to load the .hprof file of the heap dump.
The tool does not load the complete heap dump into memory at once, but loads parts when they are required. Of course, if you look around enough in the file the required memory will finally reach the size of the heap dump.
I came across an interesting tool called JXray. It provides limited evaluation trial license. Found it very useful to find memory leaks. You may give it a shot.
Try using jprofiler , its works good in analyzing large .hprof, I have tried with file sized around 22 GB.
https://www.ej-technologies.com/products/jprofiler/overview.html
$499/dev license but has a free 10 day evaluation
When the problem can be "easily" reproduced, one unmentioned alternative is to take heap dumps before memory grows that big (e.g., jmap -dump:format=b,file=heap.bin <pid>).
In many cases you will already get an idea of what's going on without waiting for an OOM.
In addition, MAT provides a feature to compare different snapshots, which can come handy (see https://stackoverflow.com/a/55926302/898154 for instructions and a description).
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?
I have a standalone program that I run locally, it is meant to be a server type program running 24/7. Recently I found that it has a memory leak, right now our only solution is to restart it every 4 hours. What is the best way to go about finding this memory leak? Which tool and method should we use?
If you are using Java from Sun and you use at least Java 6 update 10 (i.e. the newest), then try running jvisualvm from the JDK on the same machine as your program is running, and attach to it and enable profiling.
This is most likely the simplest way to get started.
When it comes to hunting memory problems, I use SAP Memory Analyzer Eclipse Memory Analyser (MAT), a Heap Dump analysis tool.
The Memory Analyzer provides a general purpose toolkit to analyze Java heap dumps. Besides heap walking and fast calculation of retained sizes, the Eclipse tool reports leak suspects and memory consumption anti-patterns. The main area of application are Out Of Memory Errors and high memory consumption.
Initiated by SAP, the project has since been open sourced and is now know as Eclipse Memory Analyser. Check out the Getting Started page and especially the Finding Memory Leaks section (I'm pasting it below because I fixed some links):
Start by running the leak report to automatically check for memory leaks.
This blog details How to Find a Leaking Workbench Window.
The Memory Analyzer grew up at SAP. Back then, Krum blogged about Finding Memory Leaks with SAP Memory Analyzer. The content is still relevant!
This is probably the best tool you can get (even for money) for heap dump analysis (and memory leaks).
PS: I do not work for SAP/IBM/Eclipse, I'm just a very happy MAT user with positive feedback.
You need a memory profiler. I recommend trying the Netbeans profiler.
One approach would be to take heap dumps on a regular basis, then trend the instance counts of your classes to try to work out which objects are being consistently created but not collected.
Another would be to switch off parts of your app to try to narrow down where the problem is.
Look at tools like jmap and jhat.
You might look up JMX and the jconsole app that ships with Java. You can get some interesting statistics out-of-the-box, and adding some simple instrumentation to your classes can provide a whole lot more.
As already stated jvisualvm is a great way to get started, but once you know what is leaking you may need to find what is holding references to the objects in question for which I'd recommend jmap and jhat, e.g
jmap -dump:live,file=heap.dump.out,format=b <pid>
and
jhat heap.dump.out
where <pid> is easily found from jvisualvm. Then in a browser navigate to localhost:7000 and begin exploring.
You need to try and capture Java heap dump which is a memory print of the Java process.
It's a critical process for memory consumption optimisation and finding memory leaks.
Java heap dump is an essential object for diagnosing memory-linked issues including java.lang.OutOfMemoryError, Garbage Collection issues, and memory leaks which are all part of Java web development process
For clarity, a Heap dump contains information such as Java classes and objects in a heap during instant of taking the snapshot.
To do it, you need to run jmap -dump:file=myheap.bin <program pid>.
To learn more about how to capture Java heat dumps, check out: https://javatutorial.net/capture-java-heap-dump