What is virtual in jvm

hi friends.
i have a basic doubt. why java runtime mechanism is said to be virtual machine. Virtual means imaginary. what is dummy in jvm.
by vinod

It is virtual, because it hides the differences between each platform.
When you develop a java program, you don't have to worry about whether it is run on an Intel processor or a Sparc processor, Windows or Unix.
The Java program, presents the java developer with a "virtual machine", as opposed to a specific platform and processor.
Ps. Virtual does not mean imaginary. In this case, it means a common interface to many platforms.
regards,
Owen

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=====================================================
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- Mike
"[email protected]" Mike wrote:
>
>
Aslo - GC[1] are taking way long (Debug JVM) - I'm used to seeing them taking
500
ms with the regular JVM. With -ms32m -m256m - I wanted GC[1] to run often
because
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so hot here.
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GC[1] in 6300 ms: (38Mb, 0% free) -> (38Mb, 65% free)
GC[1] in 7130 ms: (38Mb, 0% free) -> (38Mb, 64% free)
GC[1] in 6158 ms: (38Mb, 2% free) -> (38Mb, 62% free)
GC[1] in 6171 ms: (38Mb, 0% free) -> (38Mb, 65% free)
GC[1] in 6885 ms: (38Mb, 0% free) -> (38Mb, 64% free)
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GC[1] in 7912 ms: (38Mb, 0% free) -> (38Mb, 55% free)
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GC[1] in 6543 ms: (38Mb, 1% free) -> (38Mb, 60% free)
GC[1] in 7036 ms: (38Mb, 1% free) -> (38Mb, 59% free)
GC[1] in 7483 ms: (38Mb, 0% free) -> (38Mb, 56% free)
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GC[1] in 8186 ms: (38Mb, 0% free) -> (38Mb, 53% free)
GC[1] in 5691 ms: (38Mb, 0% free) -> (38Mb, 58% free)
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GC[1] in 8463 ms: (38Mb, 0% free) -> (38Mb, 47% free)
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GC[1] in 9865 ms: (60Mb, 0% free) -> (60Mb, 60% free)
GC[1] in 11323 ms: (60Mb, 0% free) -> (60Mb, 57% free)
GC[1] in 18768 ms: (60Mb, 0% free) -> (60Mb, 60% free)
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GC[1] in 7293 ms: (60Mb, 0% free) -> (60Mb, 42% free)
GC[1] in 9372 ms: (60Mb, 0% free) -> (60Mb, 53% free)
GC[1] in 8814 ms: (60Mb, 0% free) -> (60Mb, 55% free)
GC[1] in 9695 ms: (60Mb, 1% free) -> (60Mb, 54% free)
GC[1] in 7309 ms: (60Mb, 0% free) -> (60Mb, 53% free)
GC[1] in 8713 ms: (60Mb, 0% free) -> (60Mb, 54% free)
GC[1] in 11955 ms: (60Mb, 0% free) -> (60Mb, 55% free)
GC[1] in 12685 ms: (60Mb, 1% free) -> (60Mb, 55% free)
GC[1] in 18906 ms: (60Mb, 0% free) -> (60Mb, 58% free)
GC[1] in 13333 ms: (60Mb, 0% free) -> (60Mb, 51% free)
"[email protected]" <[email protected]> wrote:
Rob -
Thanks for your attention -
We create lots of threads - up to five threads for each DB hit (i didn't
design it).
The multi-threading will be disabled/removed and tested later on today.
Both 'top'
and pstack show around 85 threads.
I've read articles on the bea newsgroups about WL hanging on to threadreferences
so that the threads could not be GC'ed, but it sounded more like a customer's
impression
of what might be going on than something from BEA engineering.
Right now we are running with the 1.2.2_05a 'Debug' JVM with -verbose:gc
-verbose:gc
-verbose:gc
JVMARGS=verbose_c_heap,inline_instrs_jit=0
Unfortunately, some of the code being tested is now broken and not being
excercised
today. I will keep you posted.
- Mike
Rob Woollen <[email protected]> wrote:
How many threads are you creating?
Each thread uses some memory (stack etc.), but 1.9GB would be a lot of
thread creation.
-- Rob
Mike Reiche wrote:
This is on Solaris 2.6, JDK 1.2.2_05a, JDK1.2.2_07, possibly JDK 1.3
(it
crashed).
WLS 5.1, SP8. With inline_instrs_jit=0.
This is the [heap] segment shown by /usr/proc/bin/pmap. This is nativeheap, it is
NOT the Java Heap.
I know it could be the Type 2 db drivers - but I doubt it.
With JDK1.3 we set -XX:MaxPermSize=128m - it crashes after an hour.
One part of the application creates its own threads for some parallelprocessing.
Is this a known
problem with the JVMs?
Any help is much appreciated.
Mike Reiche--
Coming Soon: Building J2EE Applications & BEA WebLogic Server
by Michael Girdley, Rob Woollen, and Sandra Emerson
http://learnweblogic.com

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p.s.: This reply was in the editor when you posted an update, so the above isn't responsive to your recent progress. Sorry for that confusion. - R
Message was edited by: RayNewbie

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