WCF一段时间不调用后需要时间继续调用

Question

I developed a WCF REST Api, which uses NHibernate as Persistence Layer. I am currently using a Per-Session service, but have read that Per-Call services is the way to go on something like I am doing.

There are 2 things (probably very related) I don't like and I wish to remove about it.

1. On the first call to the api it takes like 20 seconds to respond, which may mean that it is loading the libraries and instanciating classes. Can I do this before any call takes place? I already have an static constructor on the ServiceContract implementing class, but it is not diminishing the time for it to load.

2. On subsequent calls, if I stop calling the service for about 10 minutes, the call time goes from 1 sec to over 20 seconds again. This is my biggest concern since the clients must have 30 seconds timeout which for the users it may look that the application has crashed.

How can I improve this? Do you have any tips for improving the performance on these services?

Answer 1

Seems like a clear case of IIS App Pool recycling, so it's reasonable to assume you are hosting this WCF service in IIS.

Several options:

1. Host the service outside of IIS (WCF can be hosted as a standalone Windows service)
2. Adjust the app pool recycling frequency

Answer 2

Try logging your Application_Start() and Application_End() to show times of your application start and stop. This can give you an idea if this is your problem.

Also it may be a Session_Start/End type of thing too.

If you think your site will get busier, then your application stopping and starting all the time won't be such an issue.