学步园

You can detect the restart of application and worker process by using the performance monitor. The counters to monitor are "ASP.NET/Application Restarts" and "ASP.NET/Worker Process Restarts".

For worker process restart, ASP.NET will write an entry in the eventlog to explain why (logLevel in <processModel> controls how often eventlog is written).

For application restart, however, in v1 and v1.1 there is no easy way for a customer to figure out why a restart happened.

So by listing all reasons for app restart, I hope I can help some customers to understand and avoid the restart.

For v1
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Things that causes application restart:

- The max compilation limit is reached (look for numRecompilesBeforeApprestart in machine.config)

- Physical application path of the web application has changed.

- Change in global.asax or one of the included files

- Change in machine.config

- Change in web.config in the app root

- Change inside bin directory or its subdirs

- A directory is renamed to bin, or bin is created

- Overwhelming change notifications – too many files are changed too fast in one of content directories – could happen if, for example, files are generated on the fly per request

- Change in the code-access security policy file

- The settings of various attributes in <processModel> in machine.config affect the restart/shutdown of the worker process itself. However, if you use Windows 2003, and (by default) you are NOT using IIS5 isolation mode, <processModel> is ignored. Instead, the settings in "Application Pools" in IIS manager is used.

For v1.1
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The list for v1.1 is the same as v1, with the following new conditions:

- User code called HttpRuntime.UnloadAppDomain

- Any directory under the web application folder is renamed

- Any directory under the web application folder is deleted

IIS 6.0
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If you're using IIS 6.0, and you're not using IIS 5 compatible mode, then aspnet_wp.exe will be replaced by w3wp.exe. You may want to go to IIS Manager, go to Application Pools/DefaultAppPool, and see if any of the parameters on the Recycling and Performance tabs are causing the IIS worker process (w3wp.exe) to shutdown.