RE: 100% CPU utilization, urgent

Thanks Jeff for your detailed explanation.

(Can I please have Unix back now???!)

Have a great day.
Lisa

-----Original Message-----
Sent: Monday, January 20, 2003 11:40 AM
To: Multiple recipients of list ORACLE-L

On Mon, 20 Jan 2003, Koivu, Lisa wrote:

> Thomas, thanks for your post.
>
> However I don't see where I can match the threads on NT to what I see in
> Task Manager. Am I missing something?
>
> To be more explicit, here's what I've got:
>

Lisa,

The point you're missing is that Task Manager shows _processes_ and the view is showing _threads_ . They're 2 distinct constructs. In its simplest sense a thread is an independently executing 'thread of execution' from a main task. This is how you see one process for ORACLE.EXE and its running multiple threads (PMON, SMON etc) if you look at the process using a tool such as PVIEW or PSTAT.

Processes are spawned using the CreateProcess() API call and a process then spins off multiple threads using another call such as AfxBeginThread() (in C++). The threads all operate independently of each other and the programmer must be careful when accessing common areas of memory simultaneously by different threads. This is why in a Dr. Watson dump you will see what each thread is doing and one or more of them will usually be running WaitForSingleObject() which is a WIN32 way of serializing access to shared _process_ memory.

Contrast this to the multi-process architecture that Oracle uses on Unix. The shared memory stuctures are separate from each individual _process_ and the processes use semaphores or latches to serialize access to the external memory segment.

HTH Jeff Herrick

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