Events Wait - Latch Free

Question

Hello all,
Please help me to detect this problem. It's happening in my production db.
Everyday in specific hours, users often call me report that core application performance slow.
Then I query "SELECT * FROM V$SESSION_WAIT" to check wait event.
I can see that so many latch free events (library cache). It's always return the same/almost same results everytime I run this query.
I want to know who's holding the latch, so I do this:
"SELECT l.sid, s.sql_hash_value, s.sql_address, s.osuser, s.username, s.machine, s.program, l.name
FROM V$SESSION s, V$LATCHHOLDER l
WHERE s.sid = l.sid;"
Unfortunately, there's no useful information, sometimes it returns zero result, sometimes just few records. And I can't get who's exactly holding the latch whereas the 'victim' sessions still waiting for the latch free event.
How to get SID who's holding the latch that caused session from V$SESSION_WAIT waiting ?
Once I get the SID of holder, I can check what query caused performance slow from v$sqlarea.
Please advice,
This is my system information.
OS : AIX 5.2
Oracle : Oracle 9.2.0.8
Thank you,
BSS.

Answer 1

Hello, Thanks for replying
Because it contains high wait events and I think it's one of causal factor of degradation performance.
When the application was smooth, I noticed that this view contains few wait event records.
For additional information, I've also checked these things:
IO server : there's no significant disk busy on the server
redo generation : it takes about 10 minutes to generate redo (I think it's normal)
Or if you have any idea how to identify problem when application run slowly in specific hours, please welcome to mention it here...I'm very glad if you do :)
Thanks,
BSS