Disadvantages and Advantages of DISABLE overlapped recycle of IIS

Question

Whats the disadvantages and advantages of DISABLE overlapped recycle of IIS ?

By default the option Disable Overlapped Recycling is f

Answer 1

The disadvantages of setting that to true is that your site will be down while recycling the app pool.

The advantage is the opposite :)

The only documented situation where that needs to be set to true is explained here

When applications are recycled, it is possible for session state to be lost. During an overlapped recycle, the occurrence of multi-instancing is also a possibility.

Loss of session state: Many IIS applications depend on the ability to store state. IIS 6.0 can cause state to be lost if it automatically shuts down a worker process that has timed out due to idle processing, or if it restarts a worker process during recycling.

Occurrence of multi-instancing: In multi-instancing, two or more instances of a process run simultaneously. Depending on how the application pool is configured, it is possible for multiple instances of a worker process to run, each possibly loading and running the same application code. The occurrence of an overlapped recycle is an example of multi-instancing, as is a Web garden in which two or more processes serve the application pool regardless of the recycling settings.

If your application cannot run in a multi-instance environment, you must configure only one worker process for an application pool (which is the default value), and disable the overlapped recycling feature if application pool recycling is being used.

Answer 2

It seems I found another use case for this flag. If you are forced to use the App_Code folder for compilation, issues can occur by IIS not properly recycling your app.

We had a problem where in Attribute based authentication the conversion of the identity did not work, due to the app having conflicting DLLs loaded in the app domain.

App_Code compilation does not clean old assemblies