I agree with what Riyaj has said. It helps sometimes to realize that "waits" just means essentially "OS calls." I'd expect your process is indeed doing a lot of buffer processing, using data that's already in your database buffer cache. You can confirm or refute this hypothesis quickly with a couple of snaps of v$sess_io. Cary Millsap http://method-r.com http://carymillsap.blogspot.com On Wed, Aug 6, 2008 at 12:46 PM, Riyaj Shamsudeen < riyaj.shamsudeen@xxxxxxxxx> wrote: > Hi Keith > That means that process is either running on CPU or waiting for CPU in the > run queue, to be available. May be that all buffers it is trying to access > is in buffer cache and process is running on the CPU without any waits. > > Cheers > Riyaj > The Pythian Group > blog: http://orainternals.wordpress.com > > Keith Moore wrote: > >> Oracle 9.2.0.4, Solaris >> >> We are having a production issue where user processes are very slow. We >> are >> seeing 'cache buffers chains' latch events in the 10046 trace file. >> >> What I'm not fully understanding is the long periods of unaccounted for >> time >> where the process hangs. If I do a 'tail -f' on the trace file I can see >> it >> pause for several seconds. Here is a small sample of the output: >> >> *** 2008-08-05 15:22:57.748 >> WAIT #23: nam='latch free' ela= 8 p1=16764558008 p2=98 p3=0 >> WAIT #23: nam='latch free' ela= 12 p1=16764645560 p2=98 p3=0 >> *** 2008-08-05 15:23:16.414 >> WAIT #23: nam='latch free' ela= 9 p1=16796730344 p2=98 p3=0 >> WAIT #23: nam='latch free' ela= 10 p1=16764600056 p2=98 p3=0 >> WAIT #23: nam='db file sequential read' ela= 1893 p1=66 p2=52489 p3=1 >> *** 2008-08-05 15:23:33.376 >> WAIT #23: nam='latch free' ela= 8 p1=16764602936 p2=98 p3=0 >> *** 2008-08-05 15:23:47.319 >> WAIT #23: nam='latch free' ela= 7 p1=16796666408 p2=98 p3=0 >> >> If you look at the first four lines, you see 20 seconds have elapsed but >> the >> only wait events are the two 'cache buffers chains' waits for a total of >> 20 >> microseconds. >> >> Can someone explain what is going on here and how to troubleshoot? >> >> FYI, this process is deleting and the inserting a LOB and the hot blocks >> seem >> to be in the LOB index. >> >> Thanks >> Keith >> >> -- >> //www.freelists.org/webpage/oracle-l >> >> >> >> >> > > -- > //www.freelists.org/webpage/oracle-l > > >