Has anyone seen a problem similar to the following:
We use OpenSTA to generate varying degrees of load to test our application j2ee app using JBoss/Hibernate/MSSQL.
At low levels (75 users generating approx 5000 requests/minute) the tests complete without issue. However, when we try and ramp up the test to more modest levels (150 users generating approx 10,000 requests/minute) our test fails. Most (over 99%) of all the calls are completed just fine, however on about 25 random Servlet requests (all POSTS), the parameters are null.
Checking our test we noted that OpenSTA sent each of the incorrect requests with the correct parameters. Also, using a packet sniffer on the webserver machine, we verified that the webserver received all the packets containing these parameters. However the application fails to properly process these requests since it thinks the parameters weren't submitted. We have debug code in place which logs a message once a servlet begins processing the request and can show all the parameters it received. For these cases, no parameters are there.
I'm guessing this is a load related item but being a JBoss novice I'm not sure where to really look.
We thought the problem might be related to the configuration of the HTTP connector and have played around with the acceptCount (varied from 100 to 500) and bufferSize (from default 2048 to 102400) parameters, but these didn't seem to make much of a difference. Also, we tried setting the maxKeepAliveRequests to -1 with the thought this was the issue, but alas to no avail.
The machine we are running is averaging 44% CPU utilization during the 150 user test and we have plenty of memory available (1.4 GB heap - avg 500 MB free during the test run). Also, using the same hardware we are able to test the previous version of our product using BEA Weblogic Server 7.0 (SP5) up to around 250 of these virtual users. Based on this, we know the system should be able to handle more than load than it currently can.
I'd be more than happy to deliver greater detail about specific configuration settings, just let me know.
Thanks in advance for you help.