RE: Glassfish

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

> From: Joe Sam Shirah
>
> > I have understood it is enough to "just" stow the Java stuff away in a
> > subsystem with 1Gb RAM for itself.
>
>     No offense, but that makes no sense to me except for the particular
> case
> where a particular app happens to fit.  Otherwise, you're either throwing
> away memory that could be used in other areas or not giving Java enough.

It makes less sense if the size is always 1GB, but if you size the subsystem
properly (as you would any environment) and then allocate the appropriate
memory, Java runs much better.

This is a normal consequence of i5/OS paging and work management; i5/OS
swaps out pieces of memory that haven't been used to page in pieces that are
being used, because most programs in i5/OS tend to use sequentially located
memory.  Java, on the other hand, being a heap based VM, scatters its memory
requirements throughout the heap.  This random access characteristic causes
a lot of paging.

So, in order to work and play well with i5/OS work management, it's best to
isolate your JVM in a subsystem properly sized to fit.

Joe