Friday, November 9, 2012

Load Testing & IIS Application pool

If you are doing a load testing to see if load is going to create a crash in your application pool, there is one setting worth checking.
In IIS 7 and 7.5

Go to Advanced settings for the app pool
In Rapid Fail Protection,Enable = true, set Maximum Failures=1

In IIS6
Right click on application pool->Properties
Click on Health tab
Enable Rapid fail protection should be checked and change Failures to 1

What this will help you is to catch application pool crash easliy. The default value for failures is 5.Which  means for the first 5 crashes the application pool will recover itself.So  if your goal of testing is to detect crash on load, you might need 5 times load to replicate the issue.

2 comments:

  1. Evey,

    This is good to know.

    Were you able to crash the app pool? What happens with requests, if the app pool recovers, is it a seamless recovery?

    If you made it crash, what did you need to do, overload the max connections?

    Mike

    Reply
  2. Yes Mike,I was able to crash app pool.. with a certain specific test cases.It was not with overload of max connections.One case was the vulnerability that was fixed in ColdFusion 10 update 5.
    If you have set max failures as 5 , the first five crashes will not stop the app pool... other requests will continue to get served. Windows Event viewer will have entries for crashes.

    Reply