PMON processes taking all CPU, why?

[mrmac228]

I have a 4 CPU E420 with 4 databases. When I run top I can see that there are 4 processes taking ALL available CPU. Using /usr/ucb/ps I can see that the oracle processes taking the CPU are the PMON ones for each database.

Is this normal?

(oracle version is 8.1.7 - couldn't find the oracle 8 forum, on solaris 8)

 

[sybaseguru]

It depends on what is happening in your 4 databases. pmon is there to look after and clean up the processes. My suggestion is taht if you can shutdown all databases and have a systematic approach to problem solving. That is start each instance and then look at what processes are running and what pmon is taking. You need to isolate the problem and identify whether you have idle or disconnected user processes running on your host before starting all four.

Hope this helps

 

[nassrin5]

I would be interested in answer to this problem as well. It appears that may be memory swapping going on with 4 Oracle instances

 

[mrmac228]

I stopped all the applications that had jdbc connections to the databases - pmon processes still taking all CPU.

Shutdown all databases, check cpu usage fell to 0, and restarted oracle and listener - pmon some CPU usage but not 100%

Restarted apps and bang, straight back to 100% CPU usage.

Does this imply that the apps are doing something wrong?

 

[sybaseguru]

Where are your apps running? can you do a top and send the output here. Otherwise do a "ps -ef|grep oracle". Also do "ipcs -sa|grep oracle" for counting the number of used semaphores and send the output please

 

[mrmac228]

Sybase, will do when I get back to work - on hols for a week, nice for some eh!

 

[mrmac228]

UPDATE:

Ok, I've been back for two weeks now and guess what? The problem has not re-occurred after that last db stop and start.

Just thought I'd let you know (however if it happens again I'll be back)

Cheers