IIS Worker Process Recycle without Killing w3wp

iis-7windows-server-2008worker-process

I'm running an ASP.NET application on IIS 7.

The server blissfully hums along until

An Application_Start event is raised
All requests made by currently connected users give a 'Connection_Abandoned_By_ReqQueue' error in httperrX.log
An Application_End event is raised

It looks like a worker process recycle, right?
But w3wp never died, a new w3wp never started, and no recycle was logged.

What could have caused this? And how do I prevent it from happening?

Technical details:

Windows Server 2008 R2
IIS 7
.Net v4.0 app pool with classic pipeline
Maximum 1 worker process with overlap enabled

Update

I'm encountering this situation while load-testing a web application.

Throughout this testing process, I've recycled and restarted the web server many times. Apparently, this changes the cryptographic key being using to obtain web resources, as explained here: “Padding is Invalid and cannot be removed” exception on WebResource.axd. The testing software isn't smart enough to change its requests (without significant finagling) in response to a new key.

The result of all this was that several requests were failing with .Net cryptographic exceptions. I determined I didn't care about those requests and removed them from the test. This seems to take care of the bizarre pseudo-recycling this question is about.

Two things remain unknown:

Is the recycling caused by erroring requests to WebResource.axd or by any requests to WebResource.axd?
Why does this cause the pseudo-recycle instead of a regular recycle or no recycle at all? The behavior is still undocumented.

Best Answer

Anytime a file is changed in the application folder, this can trigger an recycle of an application pool. Antivirus real-time monitors are notorious for this, but there is actually quite a large list of potential offenders. Check the following from Tess Ferrandez:

http://blogs.msdn.com/b/tess/archive/2006/08/02/asp-net-case-study-lost-session-variables-and-appdomain-recycles.aspx

In particular, you can enable the ASP.Net Health Monitoring Event to record the activity to the application event log, with the reason for the restart.

Related Solutions

Iis – automatic IIS worker process recycle fails

EDITS in bold:

You either have SharePoint or Exchange or Some Application installed/configured on the IIS Server. When recycling of the worker process happens i.e. after every 1720 minutes internally the command used is "IISRESET". But, since the recycling has taken more time than normal for graceful shutdown which exceedes the default time-out value i.e. 60 seconds and hence the event. During this recycling of the worker process you won't find any downtime as when the old process is going down a new process is created and its takes care of the new requests. Check this article How Worker Process Recycling Works

The Event seen would be something like

Event Type: Information
Event Source: W3SVC
Event Category: None
Event ID: 1074
Description: A worker process with process id of '1234' serving application pool 'sameappPool' has requested a recycle because the worker process reached its allowed processing time limit.

To overcome the issue, the recycle command should be "IISRESET /NOFORCE" such that it allows for the services to stop them gracefully.

Iis7 large worker process request queue creating process blocking aspnet.config & machine.config amended (bottleneck)

IIS Optimization and Performance Tuning is quite a broad topic, and your bottleneck(s) could be several places.

First, you can better determine what your bottlenecks are by using the Performance Monitor.

Based on what you find there, you can move on to trying the following IIS performance tuning options:

Checking your connection strings in web.config

By default, the max pool size for connection strings in a web.config file is 100, so try specifying something higher, like "Max Pool Size=200; Min Pool Size=10; Connect Timeout=45;".

Example:

<add name="SiteSqlServer" connectionString="Server=mydomain.com;Initial Catalog=myDB;User ID=DB;Password=myDB;Max Pool Size=100;Min Pool Size=10;Connect Timeout=45;" providerName="System.Data.SqlClient" />

Checking your settings in Aspnet.config

Location: C:\Windows\Microsoft.NET\Framework\v2.0.50727 and C:\Windows\Microsoft.NET\Framework64\v2.0.50727

Example:

<system.web>
    <applicationPool maxConcurrentRequestsPerCPU="5000" <!-- Default is 12 -->
             maxConcurrentThreadsPerCPU="0" <!-- Default is 0 -->
             requestQueueLimit="5000" <!-- Default is 5000 -->/>
</system.web>

Checking your settings in machine.config

Location: C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG and C:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG

processModel

Example:

<processModel 
   enable="true"
   requestQueueLimit="5000" <!-- Adjust if necessary. Default 5000 -->
   restartQueueLimit="10"  <!-- Adjust if necessary. Default 10 -->
   memoryLimit="60" <!-- Adjust if necessary. Lower for memory leaks. -->
   maxWorkerThreads="100" <!-- Default 20 -->
   maxIoThreads="100" <!-- Default 20 -->
   minWorkerThreads="40" <!-- Default 1 -->
   minIoThreads="30" <!-- Default 1 -->
/>

connectionManagement

Example:

<system.net>
  <connectionManagement>
    <add address="*" maxconnection="100" <!-- Default is 2 --> />
  </connectionManagement>
</system.net>

Best Answer

Related Solutions

Iis – automatic IIS worker process recycle fails

Iis7 large worker process request queue creating process blocking aspnet.config & machine.config amended (bottleneck)

Checking your connection strings in web.config

Checking your settings in Aspnet.config

Checking your settings in machine.config

Related Topic