>I assume no files were modified on the app root directory? Even changing permissions can initiate a recycle....
>
>This *might* apply if it's IIS7 : http://support.microsoft.com/default.aspx?scid=kb;EN-US;950573

This seems to be a bug in the way IIS 7 handles a new compilation.

I have attached the image.

You will see that at 06h00 is the time of the recycle. Thus, it might take a few minutes before the four worker processes gets loaded based on the access to the site. You see those four entries at 22/10/2013 06:00:35, 22/10/2013 06:03:35, 22/10/2013 06:09:35 and 22/10/2013 06:14:35. You can see the worker process ID represented by 588, 3332, 6512 and 6544.

Then, I sent a compilation at 11h15.

Records 22/10/2013 10:50:19, 22/10/2013 10:50:47, 22/10/2013 10:50:58 and 22/10/2013 10:55:13 will show the unloading of those four worker processes. This is the started up time and at the right the shut down time.

But, there wasn't any traffic on that Web site until 22/10/2013 11:16:18 which then triggers the loading of new worker processes.

But, the bug is with record 22/10/2013 10:50:12. I never had such notification before. This should not even be there. This is an additional log related to the unloading process and the proper unloading process is logged a little higher in the image.