AIX

Hi,

is your java app potentially 32bit like websphere or certain other apps. Than you might run into the trap with limited shared memory as this is not unlimited like for 64bit apps. To work around this, put export EXTSHM=ON in the profile of the user which runs the java application.
Further several Java apps are only allowed to consume as much (shared) memory as explicitely is allowed within the application configuration.
And yes your memory settings do not allow the system to use the memory it has. Try the settings we keep recommending -

Code:

vmo -p -o minperm%=3
vmo -p -o maxperm%=90
vmo -p -o maxclient%=90
vmo -p -o minfree=960
vmo -p -o maxfree=1088

try to mount your filesystems with noatime and consider carefully if you need to really keep things in memory - if not consider mounting the corresponding filesystem rbrw which sends back the memory into the free list as soon as the IO is completed.
Kind regards
zxmaus

eehhhmm.. that means that for example when i execute a java process without defining the heap size, the maximum size the heap will grow is 32MB? Once the heap reaches 32MB, then it will exit with an 'OutOfMemory' error. unless I set the ulimit memory to 'unlimited' then it will exceed 32MB, right?

I am trying to understand what the ulimit memory is.

pretty much yes - the ulimit sets the soft limit for the largest amount of physical memory a user's process can allocate.

Regards
zxmaus

Ok, thanks everyone.. the first thing to do now is to set the ulimit for memory to 'unlimited'. Will monitor for awhile and see if it's ok..

---------- Post updated at 02:54 PM ---------- Previous update was at 02:30 PM ----------

Ohhhkay.. i am a bit confused now..

when I am login as a normal user, e.g 'oracle' and execute 'ulimit -a', i see the memory is 32768 Kb. But when i view the /etc/security/limits file, 'oracle' user has the following limits set:

Code:

oracle:
        fsize = -1
        data = -1
        stack = -1
        core = -1
        rss = -1

If the limits are set to '-1', why is the 'memory' in ulimit not unlimited when i run 'ulimit -a' when i'm login as 'oracle' user?

currently i'm running some test on our test server first before making the changes to the production server.

new ulimits only become active if you logout/login again to the box as this user.
If you have oracle running, this would include a restart of oracle

apart from this - you are setting only soft limits which may or may not be limited by your hard limits - so if you really want unlimited memory than you need to amend your hard limits as well - so you may want to have a setting like the below in your /etc/security/limits:

Code:

rss = -1
rss_hard = -1

Regards
zxmaus

There is a file "/etc/security/limits" which steers all the ulimits. It holds all the limits in the form of stanzas. There is a "default"-stanza which values will be used if no specific value is assigned for a user.

You can change the settings via the "chuser" command (for another user) or the "ulimit" command (from within the respective user account) or even directly (as root) using a text editor.

For more information about /etc/security/limits refer to the man page accessible via man limits.

I hope this helps.

bakunin