JDK:1.2.2->Memory leaks in Class loader, Jar handling parts

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qazmlp - 10 Feb 2004 15:21 GMT

Has anybody noticed the memory leaks due to the class loader,Jar
handling parts of Java?
The heap profiling that I did for my Java process reports huge leaks
in these areas.

Here are some of the sample stacks that HAT reports:
1)
Stack
-----
TRACE 6924:
java/lang/String.<init>(String.java:Compiled method)
java/util/jar/Manifest.parseName(Manifest.java:Compiled method)
java/util/jar/Manifest.read(Manifest.java:Compiled method)
java/util/jar/Manifest.<init>(Manifest.java:Compiled method)
java/util/jar/JarFile.getManifest(JarFile.java:Compiled method)
sun/misc/URLClassPath$JarLoader.getClassPath(URLClassPath.java:Compiled
method)
sun/misc/URLClassPath.getLoader(URLClassPath.java:Compiled method)
sun/misc/URLClassPath.getResource(URLClassPath.java:Compiled method)
java/net/URLClassLoader$1.run(URLClassLoader.java:Compiled method)
java/net/URLClassLoader.findClass(URLClassLoader.java:Compiled
method)

Memory dump
-------------
percent live alloc'ed stack class
rank self accum bytes objs bytes objs trace name
132 0.10% 66.16% 54888 593 54888 593 6924 [C

2)
Stack
-----
TRACE 2776:
java/lang/String.<init>(String.java:Compiled method)
java/util/jar/Manifest.parseName(Manifest.java:Compiled method)
java/util/jar/Manifest.read(Manifest.java:Compiled method)
java/util/jar/Manifest.<init>(Manifest.java:Compiled method)
java/util/jar/JarFile.getManifest(JarFile.java:Compiled method)
sun/net/www/protocol/jar/URLJarFile.isSuperMan(URLJarFile.java:115)
sun/net/www/protocol/jar/URLJarFile.getManifest(URLJarFile.java:Compiled
method)
java/util/jar/JarFile.getInputStream(JarFile.java:Compiled method)
sun/net/www/protocol/jar/JarURLConnection.getInputStream(JarURLConnection.java:124)
java/net/URL.openStream(URL.java:818)

Memory dump
-------------
percent live alloc'ed stack class
rank self accum bytes objs bytes objs trace name
164 0.08% 69.06% 42312 452 42312 452 2776 [C

There are 30-40 such similar stacks shown in the report.

Here is the JDK version that I use:
java version "1.2.2"
Solaris VM (build Solaris_JDK_1.2.2_08, native threads, sunwjit)

Is this a known leak?
Please share if you have any information on this.

Thanks!

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Chris Smith - 10 Feb 2004 15:36 GMT

> Has anybody noticed the memory leaks due to the class loader,Jar
> handling parts of Java?
> The heap profiling that I did for my Java process reports huge leaks
> in these areas.
>
> Here are some of the sample stacks that HAT reports:

Can't say I'm really familiar with HAT, and therefore with what you are
seeing wrong with these stack traces or what they mean.

It looks to me like the objects being allocated at these traces are part
of the URLClassLoader's internal state regarding the JAR files for its
classes. I'd expect it to last potentially just as long as the
ClassLoader does before becoming collectable. Since most applications
don't cycle ClassLoader instances frequently (if at all), I'd expect
these strings would stick around for a long time... quite likely until
the application exits. If that's what you're observing, then it's not a
memory leak; it's simply the data used by the ClassLoader to do its
work.

I'd also be surprised if Strings from a manifest file really took up a
substantial amount of space, though. Are these Strings causing you
memory problems?

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MindIQ Corporation

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Andrew Thompson - 10 Feb 2004 16:34 GMT

...

> Here is the JDK version that I use:
> java version "1.2.2"
> Solaris VM (build Solaris_JDK_1.2.2_08, native threads, sunwjit)

Sorry to divert your thread qazmlp, but..

Wow! An actual 1.2 jar! I was beginning
to think that those were the product of a
fevered imagination..

I would like to add 1.2 support to my
on-line compiler. How big is it?

--
Andrew Thompson
* http://www.PhySci.org/ Open-source software suite
* http://www.PhySci.org/codes/ Web & IT Help
* http://www.1point1C.org/ Science & Technology

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JDK:1.2.2->Memory leaks in Class loader, Jar handling parts

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