[TriLUG] Memory Monitor on a Redhat system

[Robert Dale]

On 3/29/07, Tim Jowers <timjowers at gmail.com> wrote:
>    Ideas: One other silly but possible thing is to try to start another Java
> app than JBoss. Java is not enterprise-ready yet with its mem size and is
> basically limited to 3G of user space per VM so you have to run several
> instances on large RAM machines (at least that's what a BEA consultant told
> me ;-).  Also, does "sync" help to free up any space? You can also set
> swapoff to speed up the problem or even limit the RAM during boot with a
> kernel parameter in GRUB etc. Last of all, in BEA a few years back I saw a
> mem alloc exception which was actually due to a mismatch between the AIX
> system calls and the java runtime code. We just changed the Java code to
> execute another set of system calls.

Did the BEA guy say Linux isn't enterprise ready because of its memory limit?

Java does not have a memory size limit.  It's the hardware/OS.  On a
32-bit platform you can only address 4gb.  Then you need to account
for the OS - kernel and process memory - which cuts that down further
depending on the OS.  If you're stuck on 32-bit, use a 2.6 kernel to
get the most out of your ram.  Otherwise move to 64-bit.

-- 
Robert Dale