Re: [ajug-members]: Increasing JVM heap beyond 1.3GB in Win2K

[Cal Watson <jcwatso2000@yahoo.com>]

--- Barry Hawkins <ly5t5@allthingscomputed.com> wrote:
> List,
> 	Has anyone successfully managed to get a JVM heap
> size on Windows 2000 
> using the Sun 1.4.2 JVM?  Our team has a web app in
> ColdFusion MX 
> (CFMX) (long story, stay with me on the JVM thing)
> which runs on an OEM 
> version of Macromedia JRun 4.  JRun uses the 1.4.2
> JDK on Windows 2000, 
> and Macromedia recommends setting the JVM to have a
> minimum and maximum 
> JVM heap size of 1024MB.  They also recommend
> tweaking the JVM settings 
> if you need to.  However, they offer very little
> advice on doing that, 
> and the advice they do give contains broken links to
> J2ME resources.
> 	The JVM heap size for our app is nailed at an
> average of 1,473,910,395 
> bytes or ~1.36GB.  Stuff I have found with Google
> and on the Apple Java 
> mailing list indicate that the Sun JVM on Win2K will
> only get to about 
> 1.3 - 1.6GB.  Has anyone been able to successfully
> get a heap size 
> larger than that on Win2K?
> 	Along those lines, what JVMs are folks using on
> their production 
> servers in general?  Which JVMs tend to get along
> with which app 
> servers?  I'd love to hear your input.
> 
> Thanks,
> -- 
> Barry C. Hawkins
> All Things Computed
> site: www.allthingscomputed.com
> weblog: www.yepthatsme.com
> 

Barry
There is a bug in 1.4.2 where the JVM can't expand the
heap if all the memory is completely allocated and
there is no swap space available.  You might want to
try increasing the disk space allocated for virtual
memory.  

here is the info I found on Sun's Website:
The Java HotSpot VM cannot expand its heap size if
memory is completely allocated and no swap space is
available. This can occur, for example, when several
applications are running simultaneously. When this
happens, the VM will exit after printing a message
similar to the following.

   Exception java.lang.OutOfMemoryError: requested
<size> bytes

If you see this symptom, consider increasing the
available swap space by allocating more of your disk
for virtual memory and/or by limiting the number of
applications you run simultaneously. You may also be
able to avoid this problem by setting the command-line
flags -Xmx and -Xms to the same value to prevent the
VM from trying to expand the heap. Note that simply
increasing the value of -Xmx will not help when no
swap space is available.

This issue is being tracked in bug 4697804. 


I don't know if this helps at all but I figured it
couldn't hurt.  Let me know how it goes.

Cal

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