RE: Oracle Internals

[Mohan, Ross]

Title: RE: Oracle Internals

....make that "V$LATCH" to find the SLEEP1-11 columns....

-----Original Message-----
From: Mohan, Ross [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, March 14, 2001 9:06 AM
To: Multiple recipients of list ORACLE-L
Subject: RE: Oracle Internals

HP, it is sleep/wake/check. it is up to the process to acquire the
resource. AFAIK, there is no message-passing type of algorithm to
tell waiting (whether spinning or sleeping) processes when the
semaphore becomes unset ( ie the resource is available ) Sleeps
are expensive in Latchville, and you can track their occurence
via v$latch_waits and the SLEEP* columns.

hope this partial answer helps.

-----Original Message-----
From: Henry Poras [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, March 13, 2001 10:25 PM
To: Multiple recipients of list ORACLE-L
Subject: Oracle Internals

I have been rereading Steve Adam's book a bit more carefully and have a
question. Just wondering if anyone has any answers.

When talking about latch sleeps, the book states "a process sleeping for a
latch waits on its semaphore". However, latches don't support queuing and a
number of processes may be waiting for the same latch. If I am sleeping and
the latch frees, who knows I need that semaphore? Are all waiting processes
posted with the semaphores going on/off/on/off? or is no semaphore posted
and the processes go sleep/wake/check/sleep/wake/check? I can't quite
picture the details here.

Henry

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Author: Henry Poras
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