On Jun 4, 3:32 pm, David Gourley <d...@[EMAIL PROTECTED]
> wrote:
> parminde...@[EMAIL PROTECTED]
wrote:
> > I did that, but that doesn't help. I set the size to 64 megs. but the
> > VM size behaved the same way. Please let me know if there's something
> > else that can be done.
>
> > Also, can you please point me to the diff between the VM size and the
> > heap size?
>
> One additional thing you might want to look out for. If you have any
> mixed language objects (i.e. Java objects which have underlying native
> memory associated), when the object is created memory is allocated in
> both the Java heap and the C native heap. The Java heap is controlled
> by the max heap size parameter, but the C memory is simply allocated
> using malloc (and causes the JVM to grow). Typically such objects have
> a manual tidy method (often close()), with a fallback of object
> finalisation. It is important to explicitly call close() - otherwise if
> the object gets promoted to the old area, the memory will not be freed
> until the object gets garbage collected from the old area which can take
> a very, very long time (and in the worst case you may have the process
> hit a memory limit without a garbage collection occurring as only the
> Java heap's behaviour will trigger garbage collection).
>
> There are examples of such objects in the Java library (e.g. some of the
> InputStream and OutputStream classes), as well as many 3rd party
> libraries (e.g. I've seen it with database cursor implementations).
>
> So in general, if a class has a close() type method, it must always be
> explicitly called, and in a finally block (so that exceptions don't
> cause leaked resources).
>
> Cheers
>
> Dave
>
> > On May 30, 4:53 pm, Joshua Cranmer <Pidgeo...@[EMAIL PROTECTED]
> wrote:
>
> >>parminde...@[EMAIL PROTECTED]
wrote:
>
> >>>I used JProf to see that my Swing app has 40 megs of heap allocated
to
> >>>it. However, over time VM size of the java.exe process keeps on
rising
> >>>and at times hits 300 megs. I understand that the JVM may be using
> >>>this memory for internal purposes. But is there a way to limit the
> >>>size to which the VM grows?
>
> >>>In short if I need to tell my customers that when they run my app the
> >>>VM size will not grow higher than some limit. Are there any VM
> >>>parameters I can use to ensure this.
>
> >> From Sun's java command line reference (keep in mind: this is a
> >>'non-standard' option, and is only guaranteed for Java versions ~ 1.1
- 6):
>
> >>-Xmxn
> >> Specify the maximum size, in bytes, of the memory allocation
pool.
> >>This value must a multiple of 1024 greater than 2MB. Append the letter
k
> >>or K to indicate kilobytes, or m or M to indicate megabytes.
> >> (e.g. -Xmx40m)
>
> >>This is the URL for the Java 6 version of the command
line:http://java.sun.com/javase/6/docs/technotes/tools/windows/java.html#n...
>
> >>and the earlier versions can be obtained by changing the javase/6/ to
> >>j2se/1.{5,4.2,?}/
Thanks H and Dave.
So, in a nutshell, there's no way we can control the VM size, correct?
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