RE: JDBC and MTS

From: Goulet, Dick <DGoulet_at_vicr.com>
Date: Tue, 17 Jun 2003 06:45:11 -0700
Message-ID: <F001.005B2DBB.20030617061504@fatcity.com>

Mladen,

I've found MTS to be a blessing and a curse at the same time no matter what language (C, ASP, JAVA, etc...) is being used. The biggest problem with MTS is the number of idle shared servers that you have at any point in time. When you connection request is processed by the database server any statements that need execution land in the shared pool's request queue. If you have say 100 connections on the database with 10 shared servers it only takes a 10% population of active users to exhaust your pool. Yes Oracle will start additional servers up to MTS_MAX_SERVERS but don't expect it to respond rapidly. More like a snail that a rocket. You've got two options that I can safely recommend:

configure MTS_MAX_SERVERS = MTS_MIN_SERVERS = the maximum number of anticipated connections.
configure MTS_MAX_SERVERS = 2X MTS_MIN_SERVERS = 75% of the maximum number of anticipated connections

Option 3 is more fluid, but also takes more effort to maintain the desired performance. It means programming a process or job that will occasionally wake up, evaluate the load on the database's shared server population & alter the mts_servers setting of the database dynamically. It can be done, I do it, and is very successful.

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----
Sent: Monday, June 16, 2003 11:25 PM
To: Multiple recipients of list ORACLE-L

I'm not a Java expert so please forgive me my ignorance. JDBC application is facing very strange performance problems during connect. Every now and then everything appears to be hung and then, 10 minutes later, users proceed normally but with the elevated blood pressure and serious lack of patience. I was told that JDBC has it's own connection pooling mechanism and that it will start it's own dedicated server connection. It seems though that the string "SRVR=DEDICATED" has been ignored and that users are acquiring a shared server connection.
Does anybody in this group have any experience with JDBC and MTS? Version is 8.1.7.1, 64 bit on HP-UX 11 with OPS. Dispatchers are cross-registered with listeners on all 4 nodes for load balancing purposes. I found surprisingly little material on the Metalink. No network collisions, no retransmits, no timeouts can be seen from netstat -i and netstat -s. The NIC is 1GB Ethernet and I would be very surprised if approximately 100 users could kill it with a JDBC application. They could use DBA as a human sacrifice, though.

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Mladen Gogala
Oracle DBA
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Author: Mladen Gogala
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Author: Goulet, Dick
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