topic Re: Memory Problem in Operating System - Linux

Memory Problem

Vijayakumar S — Wed, 29 Dec 2004 05:28:46 GMT

Dear All,

We face MEMORY problem in our test box is a DL380 G3, the prod
box is a DL580 G2.

The Prod box is having 6 GB of RAM. It consume all the memory.
#free -mt
total used free shared
buffers cached
Mem: 5526 5519 6 105
216 2952
-/+ buffers/cache: 2349 3176
Swap: 2047 1831 216
Total: 7574 7351 222

The box is DB Server and Webserver.
Weblogic is Running.

When I analyis i think Java consume More Memory.

ps -el | sort -nr -k10 | head
040 S 2000 6438 31203 0 80 5 - 134274 rt_sig ?
00:00:00 java
040 S 2000 31284 31203 0 80 5 - 134274 rt_sig ?
00:00:24 java
040 S 2000 31283 31203 0 80 5 - 134274 rt_sig ?
00:00:23 java
040 S 2000 31282 31203 0 80 5 - 134274 rt_sig ?
00:00:22 java
040 S 2000 31281 31203 0 80 5 - 134274 schedu ?
00:00:00 java
040 S 2000 31280 31203 0 80 5 - 134274 schedu ?
00:00:09 java
040 S 2000 31278 31203 0 80 5 - 134274 schedu ?
00:00:00 java
040 S 2000 31277 31203 0 80 5 - 134274 schedu ?
00:00:00 java
040 S 2000 31275 31203 0 80 5 - 134274 rt_sig ?
00:00:00 java
040 S 2000 31274 31203 0 80 5 - 134274 rt_sig ?
00:00:00 java

Both the test and prod boxes have the same problem.
redhat-release is :
Red Hat Linux Advanced Server release 2.1AS (Pensacola)

uname -a
Linux xxxxxx 2.4.9-e.49enterprise #1 SMP Fri Aug 6 11:32:58
EDT 2004 i686 unknown

Could anybody help me what went wrong & the exact problem with
the box.

Thanks in Advance.

S.Vijayakumar

Re: Memory Problem

xyko_1 — Wed, 29 Dec 2004 07:33:41 GMT

Hi Vijayakumar,

why do you think you have a problem ? Are you facing a lot of swapping/paging activity ? Are you facing disk contentions because of i/o paging activity ?

What is your DB server ? Does your DB server has a memory cache configurations like Oracle's SGA ?

Does Weblogic has memory configuration or number of java threads that you can customize ?

To use all memory is not necessarily a problem, it may be due user's customization and may be desireble.

regarcds,
Xyko

Re: Memory Problem

Vijayakumar S — Wed, 29 Dec 2004 08:32:39 GMT

Hi Xyko,

Even though the DB is down it consumes lot of Memory or the Full 5 GB Memory.

Yes, there are many configurations in Weblogic for threads and all.

I want to confirm whatz the amount of Memory is used by JAVA.

Thanks
Vijay S

Re: Memory Problem

xyko_1 — Wed, 29 Dec 2004 10:37:17 GMT

Hi,

If there is a parameter in weblogic to configure the maximun number of java threads (i.e. the maximun number of connected clients), you may see what's the working set size of one java thread (ps shows 31203 as I can see) and make the calculation. If you don't have that parameter at all, you will have an initial value that is the number of java threads that are initiated at weblogic startup and a limit that will be defined by the memory (real and virtual=swap) capacity of your server to receive client connections before memory shortage.

But I think that your primary concern must be to verify if your server is becaming under memory stress. You will see that by a large percentage of cpu on %io wait or by a large number of page/swap activity.
top will give you %io wait
vmstat will give you paging/swap numbers

Hope it helps
Xyko