Re: [las_users] LAS Armstrong JAVA_OPTs tuning

[Roland Schweitzer <Roland.Schweitzer@xxxxxxxx>]

 Hello Penny,

Sounds like you had a lab full of teachers in for training and LAS failed.  Sorry to hear that.  I'm sure we can get this resolved.

Oots, Penny C. (LARC-E301)[SCIENCE SYSTEMS & APPLICATIONS INC.] wrote:

What values do you recommend for JAVA_OPTS parameters –Xms and –Xms for LAS Armstrong 1.1.1 when 21 users are using the server at the same time?

We were running (site http://mynasadata.larc.nasa.gov/las.armstrong/servlets/dataset) yesterday with the following:

JAVA_OPTS="-Djava.awt.headless=true –Xmx2048M –Xms2048M"

                        (by the way, these numbers worked for 20 users for LAS 6.5 at this time last year on same system which has 12G of memory)

and managed to lock up the server to the point that we could not get the user interface to display.

The memory parameters you have here are very generous and should be plenty to support 21 users.  Without any other information I would suspect that the some other problems (database connections, temporary file space, etc) lead to this problem, not server memory.  The best way to get to the bottom of this is to study the logs.  If you still have them, please cut out the entries from the start of the class until well after the time the server began to have problems.  If it's large, zip it or compress it and send it a long in an email.

If you don't have the logs we'll have to set up a test scenario to reproduce the problem.

A local sys admin recommended that we change our parameters to –Xms512M and –Xms4096M but since we are running 32-bit java, tomcat would not come up with 4096

I'd be surprised if we need that much memory.  You could cut down the initial size in when you start with 2048, but if I've always started with them the same since the old days of a bug in the JVM that surface if they were not the same.

We are also ran out of space in /tmp overnight so I’m not sure if we just have a space issue or if we should be changing JAVA_OPTS parameters.  Admins are going to reboot the system this morning.

Lack of /tmp space can certainly affect the operation of a server (not just the Tomcat, but the operation of the server itself) so that is something we need to look at carefully.

Any thoughts or guidance would be very much appreciated!

Send us you log files (catalina.out) for the time when the problem occurred and we'll study them.

Roland

 

Penny Oots
Science Systems & Applications Inc.
NASA Langley Research Center, MS 157D
Hampton, VA 23681-2199
(757) 864-9816