How do the WOrkflow Runtime and IIS App pool coincide?

Question

We are hosting worklfows with WCF and IIS 7. One thing I have noticed is that when the app pool reaches the idle time, the workflow unloads and persists to the DB.

Then when we run another workflow, the old persisted/unloaded workflow resumes itself again and both run. Why is this happening?

If you have long running workflows, do youu have to set the on idle time to more than what the longest running workflow will run for?

What is the best memory management with hosting workflows in IIS with WCF?

I know you need IIS to recycle the app pool for the memory to be released, but if you have the idle time so long, IIS will keep the memory and it doesn't do a good job of releasing the memory, even though the workflow has finished. If we make the on idle shorter it seems like IIS thinks the app pool is not doing anything and then recycles and the workflow is unloaded.

Thanks

Answer 1

Probabily IIS is configurated to Shutdown worker processes after being idle. That means when the WCF that is runnig into the application pool reach the idle time IIS shutdonw the workprocess w3wp.exe and the WCF persist Itself. When you run the second workflow the w3wp.exe will be started again that why you can see both the WCF running again but if one of them reach again the idle time IIS will shutdown again the w3wp.exe process.