Thanks Jeff for your detailed explanation.
(Can I please have Unix back now???!)
Have a great day.
Lisa
-----Original Message-----
From: Jeff Herrick [mailto:[EMAIL PROTECTED]]
Sent: Monday, January 20, 2003 11:40 AM
To: Multiple recipients of list ORACLE-L
Subject: RE: 100% CPU utilization, urgent
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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