[Iplant-api-dev] What are the best practices for getting 4-8GB java JVMs for testing?

[Rion Dooley]

I don't believe you can guarantee that any head node will have 4-8GB free at any given moment. They are shared nodes, so you only have available what is available when you run the command. Generally speaking, you shouldn't be running a java process that takes 4-8gb of memory on the head node. Just start an interactive session with one of the worker nodes or use atmosphere/rodeo.

Rion










________________________________________
From: iplant-api-dev-bounces at iplantcollaborative.org [iplant-api-dev-bounces at iplantcollaborative.org] on behalf of Damian Gessler [dgessler at iplantcollaborative.org]
Sent: Wednesday, December 11, 2013 1:37 PM
To: Rion Dooley
Cc: iPlant API Developers Mailing List
Subject: [Iplant-api-dev] What are the best practices for getting 4-8GB java    JVMs for testing?

Lonestar appears to be running tight today.

Per Rion's response yesterday on allocating a JVM, this worked yesterday:

 > login1$ java -Xmx5099m -version
 > java version "1.7.0_45"
 > Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
 > Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

but today it fails:

        login2$ hostname
        login2.ls4.tacc.utexas.edu
        login2$ module load java64
        login2$ java -Xmx5099m -version
        Error occurred during initialization of VM
        Could not reserve enough space for object heap
        Error: Could not create the Java Virtual Machine.
        Error: A fatal exception has occurred. Program will exit.

Some experimenting (even w/ 32-bit jdk32 and 4GB limit) shows spotty
behavior, with sometimes even quite small allocs failing.

A snapshot of top(1) on lonestar shows:

        ...
Mem:  24675392k total, 24632400k used,    42992k free,   221316k buffers
Swap:        0k total,        0k used,        0k free, 16030668k cached
        ...

which is way tight and is perhaps ?? why mem alloc is failing.

But when I log into stampede or longhorn, none of my home files are
available (must be mounting a different home dir).

Question:

As a best practice, onto which machine should I login so as to get
reliable 4-8GB java64 mem alloc for fAPI testing applications? (If it is
stampede or longhorn, I can copy files to home no prob).

Damian.
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