ASP Caching May Cause "Server Too Busy" Errors and Blank Pages

ID: Q188352

The information in this article applies to:

Microsoft Internet Information Server version 4.0

SYMPTOMS

ASP caching in low memory situations may cause "Server Too Busy" errors and/or blank pages returned to client browsers. Memory usage by the Inetinfo process will be very high.

CAUSE

This problem occurs because too much data is being cached and the default number of ASP files to cache is set to unlimited in Internet Information Server (IIS) 4.0. ASP attempts to cache ASP files until the process runs out of virtual memory. The IIS computer stops processing pages and returns the "Server Too Busy" error or blank pages to client browsers.

Note that there are other causes of the "Server Too Busy" errors.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:

http://www.microsoft.com/Windows/ServicePacks/

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was first corrected in Windows NT 4.0 Service Pack 6.

MORE INFORMATION

ASP has been modified to flush the cache when it receives an "Out of Memory" error. This enables it to recover gracefully. Please see the following paragraphs for information on how to do additional tuning of the ASP cache, so that it does not flush the ASP cache frequently, thus nullifying the benefits of caching.

Tune the AspScriptFileCacheSize (the number of ASP files to cache) settings for IIS. This setting is documented in IIS Help. The settings depend on a number of factors, including the amount of data in the server- side Include files and the number of ASP files that are cached. It is reasonable to start with a number like 250, and then monitor the ASP cache hit ratio using Performance Monitor. If it is below 90 percent, then raise the number. If it is above 90 percent, then any changes to the Web's pages can and will most likely change the tuning parameters.

To change the ASP process options, do the following:

Open the IIS MMC.

Right-click on the computer name for the IIS computer.

Edit the master properties for the WWW Service.

Click the Home Directory tab.

Click the Configuration button.

Click the Process Options tab.

Modify the settings in the Script File Cache group.

NTDLL may not efficiently use the virtual address space, which causes the processes to run out of memory sooner. Apply the fix listed in the following article in the Microsoft Knowledge Base:

Q216383 Memory Allocations May Fail When There Are Large Free Blocks

Some improvement can be made by increasing the per-process address space from 2 GB to 3 GB. For additional information, please see the following article in the Microsoft Knowledge Base:

Q171793 Information on Application Use of 4GT RAM Tuning

Note that more physical RAM may be required to reduce possible paging after this change is made.

Redesign the Web application.

Disable ASP caching.

Additional query words: 4.00

Keywords :
Version : winnt:4.0
Platform : winnt
Issue type : kbbug