Re: A single dedicated server shared between multiple sessions?

Billy Verreynne <vslabs_at_onwe.co.za> schreef in berichtnieuws 1a75df45.0308102105.9d1c8b_at_posting.google.com...
| vafanassiev_at_aapt.com.au
| >
| > I noticed that while we have 500 - 700 sessions the number of
| > dedicated server processes is much lower. It appears that
| > a single dedicated server (a process with name "oracleSID")
| > is shared between all sessions started by the same user (from
| > the same parent form).
|
| That does not sound correct. Every session that is opened requires its
| own shadow process when using dedicated server mode.
|
| Look at v$process - that is a distinct reflection of the Oracle o/s
| processes. The SPID column contains the Unix PID. Now if what you are
| saying is true, you will not have a 1:1 relationship between a user
| v$process and v$session. The SERVER column in v$session will tell you
| whether or not it is a dedicated.
|
| Oh yeah - and make pretty sure that you do ps and grep correctly when
| looking for the list of shadows. Not all of these will necassarily run
| as the Unix Oracle user.
|
| --
| Billy

It *IS* correct, even in dedicated server mde. When you start Oracle Forms you get a server process (can be found in V$PROCESS and as a Unix "oracleSID" process) and one session (can be found in V$SESSION). For each new window the user opens a new session is created within the *same* server proces. You can find the relation by joining V$SESSION.PADDR = V$PROCESS.ADDR. In this database the init.ora parameter sessions (which defaults to 1.1*processes+5) must be given a higher value. An average of 3 - 4 sessions per process is not unusual. And very efficient because having many many processes on Unix can be cumbersome. I wonder if this database performs better in MTS mode..... Have you ever checked the sar output if there is a runqueue? If there is you may want to try to run MTS. Configure mts_servers = mts_max_servers = about 1.5 * number of cpu's in the Unix server. I have the experience (on a box with 12 cpu's) with the same number of users/sessions running Forms that waiting on a shared server gives better performance than more shared servers waiting to get cpu time. Make sure batch programs keep making dedicated connections. Received on Mon Aug 11 2003 - 03:27:17 CDT