things that come to mind are queries that result in full table scans. generally, a sql query with like or contains often results in full table scan. queries that do text scanning or parsing often results full table scan.
since you're using TOAD and oracle, one thing to keep in mind is the semiphore settings. Depending on which version of Oracle you're running, you may need to tune the connection pooling setting and semiphore settings. The semiphore setting especially. If you use the create database wizard and chose a database for web application, it usually isn't tuned for moderate concurrency. 20 concurrent isn't light, but it's not what most Oracle DBA's consider moderate either. Most experienced Oracle DBA's I've known deal with hundreds of concurrent queries on really big servers and thousands of concurrent connections. since you're using TOAD, have you tried toad's sql profiling capabilities? peter On 5/4/05, Thinh Nguyen <[EMAIL PROTECTED]> wrote: > > Thanks for your kindly responses to both Sebbaz and Peter. > > 80 seconds were the average of the 20 concurrent users. The first few > threads finished in approximately 30 seconds, some were between 70, 80 > seconds, some were more.. > > I came to the same conclusion, however, the question I'd like to ask is that > given that the query can be bad, the performance for 1 user x 20 times > average is almost 10 less than 20 concurrent users while using the same > query. > > When I used SQL PLUS to test the query, the results were displayed after 2 > seconds. Similar results were achieved by TOAD. This query was then copied > to JDBC sampler, and the results were mentioned as above. > > The machine where WAS is running has 2G of RAM, 2 processors, and while > running the test memory was increased from 555MB to around 1.5G and then > stable. The worst part is the memory usage stayed at 1.5G and didn't drop > down, looks like a memory leak somewhere in the app (given that it's J2EE > app, but this is another issue). The client that runs JMeter is V880 (unix > machine), it's very powerful box. I've also run JMeter on 1G of RAM, Windows > XP with JDK1.5. Similar results were achieved. > > I am really running out of ideas, please kindly provide further help. > > Thanks & regards, > Thinh > > >From: sebb <[EMAIL PROTECTED]> > >Reply-To: sebb <[EMAIL PROTECTED]> > >To: JMeter Users List <jmeter-user@jakarta.apache.org> > >Subject: Re: Concurrent users > >Date: Wed, 4 May 2005 11:15:14 +0100 > > > >One way to get some idea if JMeter is coping with the load is to > >replace the HTTP/JDBC samplers with JavaTest samplers (using suitable > >sleep times). > > > >If JMeter can't cope on your system with these samplers, it's unlikely > >to be able to cope with the original samplers. > > > >Either way, be sure to have a look at the resource usage on the system > >(CPU, memory) to see how close you are to the limits. > > > >Also, if your test is quite short, beware of startup/shutdown > >overheads. These can seriously affect throughput calculations. > > > >To improve JMeter maximum capability: > >- Use as few Listeners as possible. > >- use non-GUI mode with no Listeners (one is added automatically). > > > >S. > >On 5/4/05, Thinh Nguyen <[EMAIL PROTECTED]> wrote: > > > Hi all, > > > > > > I've started to use JMeter for the last 2 weeks or so. I am trying to do > > > some performance testing with 1 user multiple times (eg 20) and 20 > > > concurrent users at 1 time. > > > > > > The results that I received for the two scenarios are too much > >different. An > > > average of a user 20 times is around 5 seconds, whereas, average for 20 > > > concurrent users at 1 time is around 80 seconds. > > > > > > I understand that concurrent users will be slower, but I don't expect it > >to > > > be that much slower. I am not sure if this problem is part of the tool > >or > > > it's with the code. > > > > > > I even tried to run the JDBC testing, and the average result are still a > >lot > > > different from 1 user * 20 times compared to 20 users at 1 time. > > > > > > Could anyone please kindly explain to me or direct me to somewhere that > >I > > > can read/reduce the performance for concurrent users? I am facing the > >hurdle > > > at the moment, please kindly help. > > > > > > Thanks & Regards, > > > Thinh > > > > > > _________________________________________________________________ > > > REALESTATE: biggest buy/rent/share listings > > > http://ninemsn.realestate.com.au > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > >--------------------------------------------------------------------- > >To unsubscribe, e-mail: [EMAIL PROTECTED] > >For additional commands, e-mail: [EMAIL PROTECTED] > > > > _________________________________________________________________ > REALESTATE: biggest buy/rent/share listings > http://ninemsn.realestate.com.au > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
