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optimal Connection pool size?

babu lingam

Joined: Nov 21, 2002
Posts: 4
I am having WAS 3.5.3 running on Windows 2000, Oracle 8.1.7 database on a UNIX box. I am having 200 client application hitting the WAS box through a Servlet. Each application opens 4 connections directly from the oracle DB for some non WebSphere activity (as the client apps are written in VJ++, they use ADO to connection to the DB). Also, a few modules in the client apps post to the Servlet which needs 3 DB connections on an average.
So if one client app is running it requires 4 (thro ADO) + 3 (thro WebSphere Connection Pool) = 7 connections.
For 200 clients running concurrently 200 X 7 = 1400 connections are needed in the Oracle DB.
Is it reasonable to set
1)processes = 150 in init.ora in the oracle
2)Min Connection pool size = 10; Max Connection pool size = 600 in Datasource property of WAS.
The numbers ‘1400’ and ‘600’ looks huge.
Considering the performance how much will be optimal value for each of the settings?
I found this in WAS info center :
Rule Of Thumb to calculate Max connectin pool size:
n* (T * (C - 1) + 1)
T = no of threads
n = no. of client apps. Which initiates these threads
C = no. of DB connections opened by each thread
Applying this formula in my case 200*(1*(3-1) +1) = 600.
Any suggestions would be helpful
Thanks in advance
Michael Ernest
High Plains Drifter

Joined: Oct 25, 2000
Posts: 7292

Moving to WebSphere forum

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- Robert Bresson
Michael Zalewski
Ranch Hand

Joined: Apr 23, 2002
Posts: 168
If your init.ora says max 150 processes, you cannot have 200 clients opening 200 x 4 connections. Number of clients would only be the number of clients simultaneously connected to WAS, processing a request. If there are 200 active sessions, and if it takes the user 2 minutes to complete a page on the client, and if the response time is 5 seconds, you probably have like 100 connections max. (which is probably how your processes got increased to 150).
Kyle Brown
Ranch Hand

Joined: Aug 10, 2001
Posts: 3892
Michael is right -- given 200 clients TOTAL I would guess the actual # of simultaneous threads is closer to 20.

Kyle Brown, Author of Persistence in the Enterprise and Enterprise Java Programming with IBM Websphere, 2nd Edition
See my homepage at for other WebSphere information.
I agree. Here's the link:
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