What can cause an IIS application to reset?

Question

I am monitoring my site with a healthMonitoring section. I see a message...

Event code: 1002 
Event message: Application is shutting down. Reason: Hosting environment is shutting down. 
Event time: 8/8/2011 3:29:59 PM 
Event time (UTC): 8/8/2011 8:29:59 PM 
Event ID: 6879adf29cdc403ba8ad2e5694b6cee0 
Event sequence: 730 
Event occurrence: 1 
Event detail code: 50002 

I am having trouble determining why it is getting shut down. My app pool is set to reset every 24 hours. My web.config sessions are set to expire after 4 hours (which shouldn't affect app shutdown anyway). I saw some posts mention that healthMonitoring settings can reset an application, but I don't see any specific setting there that would do that. Also, I noticed this problem before I added the healthMonitoring section.

Just for reference, here is how it reads...

    <healthMonitoring>
        <bufferModes>
            <add name="Critical Notification" maxBufferSize="100" maxFlushSize="20"
                    urgentFlushThreshold="1" regularFlushInterval="Infinite" urgentFlushInterval="00:01:00"
                    maxBufferThreads="1" />
            <add name="Notification" maxBufferSize="300" maxFlushSize="20"
                    urgentFlushThreshold="1" regularFlushInterval="Infinite" urgentFlushInterval="00:01:00"
                    maxBufferThreads="1" />
            <add name="Analysis" maxBufferSize="1000" maxFlushSize="100"
                    urgentFlushThreshold="100" regularFlushInterval="00:05:00"
                    urgentFlushInterval="00:01:00" maxBufferThreads="1" />
            <add name="Logging" maxBufferSize="1000" maxFlushSize="200" urgentFlushThreshold="800"
                    regularFlushInterval="00:30:00" urgentFlushInterval="00:05:00"
                    maxBufferThreads="1" />
        </bufferModes>

        <providers>
            <add name="EventLogProvider" type="System.Web.Management.EventLogWebEventProvider,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a" />
            <add connectionStringName="LocalSqlServer" maxEventDetailsLength="1073741823"
                    buffer="false" bufferMode="Notification" name="SqlWebEventProvider"
                    type="System.Web.Management.SqlWebEventProvider,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a" />
            <add name="WmiWebEventProvider" type="System.Web.Management.WmiWebEventProvider,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a" />
        </providers>

        <profiles>
            <add name="Default" minInstances="1" maxLimit="Infinite" minInterval="00:01:00"
                    custom="" />
            <add name="Critical" minInstances="1" maxLimit="Infinite" minInterval="00:00:00"
                    custom="" />
        </profiles>

        <rules>
            <add name="All Errors Default" eventName="All Errors" provider="EventLogProvider"
                    profile="Default" minInstances="1" maxLimit="Infinite" minInterval="00:01:00"
                    custom="" />
            <add name="Failure Audits Default" eventName="Failure Audits"
                    provider="EventLogProvider" profile="Default" minInstances="1"
                    maxLimit="Infinite" minInterval="00:01:00" custom="" />
            <add name="Application Lifetime Events Default"
                     eventName="Application Lifetime Events"
                     provider="EventLogProvider"
                     profile="Default"
                     minInstances="1"
                     maxLimit="Infinite"
                     minInterval="00:01:00"
                     custom="" />
        </rules>

        <eventMappings>
            <add name="All Events" type="System.Web.Management.WebBaseEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Heartbeats" type="System.Web.Management.WebHeartbeatEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Application Lifetime Events" type="System.Web.Management.WebApplicationLifetimeEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Request Processing Events" type="System.Web.Management.WebRequestEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="All Errors" type="System.Web.Management.WebBaseErrorEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Infrastructure Errors" type="System.Web.Management.WebErrorEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Request Processing Errors" type="System.Web.Management.WebRequestErrorEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="All Audits" type="System.Web.Management.WebAuditEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Failure Audits" type="System.Web.Management.WebFailureAuditEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
            <add name="Success Audits" type="System.Web.Management.WebSuccessAuditEvent,System.Web,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b03f5f7f11d50a3a"
                    startEventCode="0" endEventCode="2147483647" />
        </eventMappings>

    </healthMonitoring>

What could be causing my application to reset?

Thanks!

Answer 1

IIS can reset/restart for many reasons. From Tess Ferrandez's blog:

• Machine.Config, Web.Config or Global.asax are modified
• The bin directory or its contents is modified
• The number of re-compilations (aspx, ascx or asax) exceeds the limit specified by the setting in machine.config or web.config (by default this is set to 15)
• The physical path of the virtual directory is modified
• The CAS policy is modified
• The web service is restarted
• (2.0 only) Application Sub-Directories are deleted

IIS will shutdown your application if it is idle (the default is 20 minutes of no activity), has consumed too much memory or CPU time.

Also anti-virus programs running on the web server have been blamed for resetting IIS, I assume by touching any of the files/directories that are mentioned above.

Answer 2

I was going over the same issues, and I started looking in other server logs to see if something else happened at the exact time of the recycle.

in the System event logs I found this:

A worker process with process id of '6600' serving application pool 'Version 1.2' has requested a recycle because the worker process reached its allowed processing time limit.

the source was: WAS

(Windows Process Activation Service)

I know that the reasons could vary, but for future references, one should look at other logs as well.