Reputation: 9691

How to dynamically monitor Java heap size?

I am trying to monitor the java heap size dynamically. Does anybody know how to get the maximium memory used in the process of running a piece of codes? Does the Runtime.maxMemory() do the trick? Thanks

Upvotes: 40

Answers (9)

MRalwasser

Reputation: 15953

Maybe jvmtop is worth a look. It's a command-line tool which provides a live-view at several metrics, including heap size:

 JvmTop 0.4.1 alpha amd64  8 cpus, Linux 2.6.32-27, load avg 0.12
 http://code.google.com/p/jvmtop

  PID MAIN-CLASS      HPCUR HPMAX NHCUR NHMAX    CPU     GC    VM USERNAME   #T DL
 3370 rapperSimpleApp  165m  455m  109m  176m  0.12%  0.00% S6U37 web        21
27338 WatchdogManager   11m   28m   23m  130m  0.00%  0.00% S6U37 web        31
19187 m.jvmtop.JvmTop   20m 3544m   13m  130m  0.93%  0.47% S6U37 web        20
16733 artup.Bootstrap  159m  455m  166m  304m  0.12%  0.00% S6U37 web        46

Upvotes: 2

user1529891

Reputation:

I'd also like to add that jmap -heap <PID> does the trick; that is assuming you're an ops guy and need to know how much heap the Java process is using. I cant tell if your question is programmatical, or operational.

Upvotes: 9

agonen

Reputation: 311

jstat -gc <pid> <time> <amount>

jstat -gc `jps -l | grep weblogic\.Server | awk {'print $1'}` 1000 3

3 samples 1 one second see more here

Upvotes: 12

helios

Reputation: 13841

If you like you can visually view a lot of values profiling your app with JConsole.

http://docs.oracle.com/javase/6/docs/technotes/tools/share/jconsole.html

Start your application with:

-Dcom.sun.management.jmxremote

and you app will be available for select when you start /bin/jconsole.exe

Upvotes: 12

Jacob Schoen

Reputation: 14212

maxMemory() returns the maximum amount of memory that java will use. So That will not get you what you want. totalMemory() is what you are looking for though. See The docs

Upvotes: 32

Kees Jan Koster

Reputation: 26

Yet another free alternative is to use Java-monitor. Have a look at this live demo. Just click on any of the servers to see detailed graphs on heap memory, non-heap memory, file descriptors, database pools and much more.

Upvotes: 0

pschiffer

Reputation: 11

We use app internals xpert by OpNet to monitor heap usage and leaks in realtime in our load testing environment and production. It's lightweight enough to not impact prod, so we get great data we can't get from QA. We also do profiling of methods and db calls in both environments to help us figure out what code/sql to optimize. Very cool stuff with pretty trend charts, but not free by any stretch. If you've got a lot of dollars riding on your app, it's worth the investment.

http://www.opnet.com/solutions/application_performance/appinternals-xpert.html

Upvotes: 1

user85421

Reputation: 29680

There is also the java.lang.management package. Use the ManagementFactory to get an MemoryMXBean instance. It has methods to return a heap and a non-heap memory usage snapshot.

Upvotes: 4

Hank Gay

Reputation: 71949

There are a large number of profiler tools available that should help you with this. A popular commercial tool is YourKit, and it gets rave reviews. A free alternative is VisualVM, which I've used in the past and can provide a lot of insight.

Upvotes: 13

How to dynamically monitor Java heap size?

Answers (9)

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