A process serving application pool suffered a fatal communication error with the Windows Process Activation Service.

Why does Application Pool Crashes Sometimes?
I was getting this error on my server

Log Name:      Application
Source:        Application Error
Date:          12/6/2011 3:57:47 PM
Event ID:      1000
Task Category: (100)
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      XXX
Description:
Faulting application name: w3wp.exe, version: 7.5.7601.17514, time stamp: 0x4ce7a5f8
Faulting module name: KERNELBASE.dll, version: 6.1.7601.17651, time stamp: 0x4e211319
Exception code: 0xe053534f
Fault offset: 0x0000b9bc
Faulting process id: 0x%9
Faulting application start time: 0x%10
Faulting application path: %11
Faulting module path: %12
Report Id: %13
Event Xml:

 
   
    1000
    2
    100
    0x80000000000000
   
    73326
    Application
    XXX
   
 
 
    w3wp.exe
    7.5.7601.17514
    4ce7a5f8
    KERNELBASE.dll
    6.1.7601.17651
    4e211319
    e053534f
    0000b9bc
 

and after this i usually get an error


"A process serving application pool 'XXX' suffered a fatal communication error with the Windows Process Activation Service. The process id was '1234'. The data field contains the error number."





I am running an ASP.NET Framework 3.5 under integrated environment web application on IIS 7.5 on Windows Server 2008 R2.Sometimes i get this error  When access to the website, it raise error message: ‘HTTP Error 503. The service is unavailable.’.

I am still working on this issue and got some temporary measures that delay this error
measures taken under Application pool advanced settings changed the settings :
1)   Maximum worker processes to 2 and made it a Web Garden
2)  Changed the Rapid failed protection Failure interval to 2
3)  And lastly changed the Recycling regular time interval from 1740 (default) to 1000.

since that time its working properly but for a quick measure when you are facing this issue
 go to the Internet Information Services (IIS) Manager to recycle my Application Pool again. it would work properly .

What is webgarden and Application Pool?

Question -> What is webgarden and Application Pool?
Answer.
Webgarden ->A Web garden is configured on a single server by specifying multiple worker processes for an application pool.

Application Pool ->An Application Pool can contain one or more applications and allows us to configure a level of isolation between different Web applications. For example, if you want to isolate all the Web applications running in the same computer, you can do this by creating a separate application pool for every Web application and placing them in their corresponding application pool. Because each application pool runs in its own worker process, errors in one application pool will not affect the applications running in other application pools. Deploying applications in application pools is a primary advantage of running IIS 6.0 in worker process isolation mode because you can customize the application pools to achieve the degree of application isolation that you need.


Question ->Where to set webgarden in IIS?
Answer :
1) Configuring Web Gardens with IIS 6.0
This feature of IIS 6.0 is available only when IIS is running in worker process isolation mode.
To configure a Web garden by using IIS Manager
A.
In IIS Manager, expand the local computer, expand Application Pools, right-click the application pool, and then click Properties.
B.
Click the Performance tab, and under Web garden, in the Maximum number of worker processes box, type the number of worker processes that you want to assign to the application pool. (You must type a number greater than 1 for the application pool to become a Web garden.
C.
Click OK.

2) Configuring Web Gardens with IIS 7.0 and IIS 7.5(windows server 2008   )

This feature of IIS 6.0 is available only when IIS is running in worker process isolation mode.

To configure a Web garden by using IIS Manager
A.
In IIS Manager, expand the local computer, expand Application Pools, right-click the application pool, and then click Advanced Settings.
B.
Under Process Model,in the Maximum number of worker processes box, type the number of worker processes that you want to assign to the application pool. (You must type a number greater than 1 for the application pool to become a Web garden.
C.
Click OK.

To configure a Web garden by using Adsutil.vbs
A.
In the Run dialog box, type cmd, and then click OK.
B.
At the command prompt, type:
cscript %SystemDrive%\Inetpub\AdminScripts\adsutil.vbs set W3SVC/AppPools/ApplicationPoolName/MaxProcesses n
Replace n with the number of worker processes that you want to service the application pool.