topic Re: Free memory from unused processes in Operating System - HP-UX

Free memory from unused processes

Subentu — Wed, 18 Nov 2009 06:48:55 GMT

Hi Guys,

Is there any way to free the memory allocated for processes that are not running?

Thanks in advance

Re: Free memory from unused processes

Aneesh Mohan — Wed, 18 Nov 2009 06:53:36 GMT

Hi,

Gracefully stop the process.

Aneesh

Re: Free memory from unused processes

Subentu — Wed, 18 Nov 2009 07:04:23 GMT

But if I don't know which processes are running and which are idle, is there any way to do it?

I have a lot of oracle processes (about 100), and im sure some of them are idle. But there is no way to know which.

Re: Free memory from unused processes

Dennis Handly — Wed, 18 Nov 2009 07:39:39 GMT

>Is there any way to free the memory allocated for processes that are not running?

What do you mean by "free"? The kernel will page out unused pages automatically.
The kernel won't give up the swap space.

What are you trying to solve?

Re: Free memory from unused processes

Venkatesh BL — Wed, 18 Nov 2009 08:01:09 GMT

What is the real issue? Are you facing memory crunch? What does 'glance' tell you?

Re: Free memory from unused processes

Subentu — Wed, 18 Nov 2009 18:32:28 GMT

I have a lot of oracle processes running in my server, and i suspect that some of them are idle.

Is there any way to claim back the memory occupied by them? or the OS automatically claims back it?

Re: Free memory from unused processes

Aneesh Mohan — Wed, 18 Nov 2009 18:35:40 GMT

Hi,

>>I have a lot of oracle processes running in my server, and i suspect that some of them are idle.

My suggestion is don`t try to disturb any of the oracle process from OS ,it can make your database inconsistent .

You can advise you DBA to enable session timeout / kill snipped session to release the idle resources.

Aneesh

Re: Free memory from unused processes

Dennis Handly — Sat, 21 Nov 2009 16:41:24 GMT

>or the OS automatically claims back it?

Yes, the kernel will reclaim memory (unless locked) but not swap.

Re: Free memory from unused processes

Bill Hassell — Sat, 21 Nov 2009 17:53:21 GMT

If a process is shown in ps then it is running. There is no concept of an 'idle' process. If a process is not necessary, then youe database administrator needs to determine what is not needed. A process may be waiting for someone to type on a keyboard but if you were to remove the memory used by the process, the process will crash.

Processes that are waiting for some event will be lowered in priority and eventually be deactivated automatically and paged out to your swap area but only if your system is running short of RAM. Note that if you are trying to solve error messages regarding out of memory, this is very likely not related to memory usage but instead due to limits set in your kernel that need to be increased, or perhaps increasing swap space. What if the output of:

swapinfo -tam

Re: Free memory from unused processes

Dennis Handly — Sat, 21 Nov 2009 19:03:21 GMT

>Bill: If a process is shown in ps then it is running.

I wouldn't exactly say that. It could be sleeping or waiting. My definition of running is using the CPU.
All you can tell if it shows in ps(1), is he's not dead, Jim. :-)

Re: Free memory from unused processes

James R. Ferguson — Sat, 21 Nov 2009 19:12:49 GMT

Hi:

> Dennis: All you can tell if it shows in ps(1), is he's not dead, Jim. :-)

While I'm sure you weren't addressing me :-) I would add that zombies show in 'ps' as "defunct". Of course, they don't have any user or kernel space allocated, and they are doomed to await their Grim Reaper.

Regards!

...JRF...