Hello,
I have a webtest with makes a simple call to a WebService which looks like that:
MyWebService webService = new MyWebService();
webService.Timeout = 180000;
webService.myMethod();
I am not using ThinkTimes, also the Run Duration is set to 5 minutes. When I ran this test simulating only 1 user, I check the counters and I found something like that:
Tests Total: 4500
Network Interface\Bytes sent (agent machine): 35,500
Then I ran the same tests, but this time simulating 2 users and I got something like that:
Tests Total: 2225
Network Interface\Bytes sent (agent machine): 30,500
So when I increased the numbers of users the tests/sec was half than when I use only 1 user and the bytes sent by the agent was also lower. I think it is strange, because it doesn't seems I have a bottleneck in my agent machine since CPU is never higher than 30% and I have over 1.5GB of RAM free, also my network utilization is like 0.5% of its capacity.
In order to troubleshot this I ran a test using Step Pattern, the simulated users went from 20 to 800 users. When I check the requests/sec it is practically constant through the whole test, so it is clear there is something in my test or my environment which is preventing the number of requests from gets higher.
It would be a expected behavior if the "response time" was getting higher because it would tell me the requests wasn't been processed properly, but the strange thing is the response time is practically constant all the time and it is pretty low actually.
I have no idea why my agent can't send more requests when I increase the numbers of users, any help/tip/guess would be really appreciate.