Important: Oracle processes taking lots of CPU
- From: New DBA <new_dba_on_the_block@xxxxxxxxx>
- To: ORACLE-L@xxxxxxxxxxxxx
- Date: Tue, 23 Nov 2004 02:57:08 -0800 (PST)
Hi all,
Please forgive my ignorance if the details provided by
me are not sufficient, or I'm not doing proper
analysis.
11.5.8 on 9.2.0.5 O/s HP-UX Risc 64 B.11.11
We are facing a unique problem. Lots of DB processes
take close to 100% CPU and an overall CPU time of more
than 500 mins. This happens with lots of different
applications/forms. The problem doesn't happen all the
time i.e. if the same form is run 10 times, only 1-2
faces that kind of problem.
With my limited knowledge I've been able to get the
following details about the problem.
The DB processes take a huge amount of CPU time. This
fact is not reflected in v$sesstat or the 10046 trace
files. There are processes which take more than 500
mins. of CPU time, but the trace file doesn't account
for even a tiny fraction of that.
When monitoring the process at the OS, the process
takes close to 100% CPU all the time, but the CPU
stats in v$sesstat doesn't increase.
I did a truss on the processes consuming 100% CPU and
it shows the following line repeating infinitely:
select(2048, 0x800003fffdffb3d0, 0x800003fffdffb4d0,
0x800003fffdffb5d0, 0x800003fffdffb6d0) = 0
v$session_wait shows some wait event like "latch
free", "db file sequential read" but with STATE =
waited known time, but the seconds_in_wait keeps
increasing while the process keeps taking 100% CPU all
the while.
Please let me know if anyone has faced a similar
issue. How do I find out what is the process doing
which is eating up all the CPU?
I think that the problem is somehow at the O/S level,
since trace files don't indicate anything wrong, same
forms when run again, run without taking much CPU.
Regards
New DBA
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