PRB: Request Forwarding Sometimes Does Not Forward Some Requests on Windows Server 2003 when IIS 6 Runs in Worker Process Isolation Mode (820456)



The information in this article applies to:

  • Microsoft Application Center 2000 SP2
  • Microsoft Internet Information Services version 6.0
  • Microsoft Windows XP 64-Bit Edition Version 2003
  • Microsoft Windows Server 2003, Enterprise Edition
  • Microsoft Windows Server 2003, Standard Edition

SYMPTOMS

When a Microsoft Windows Server 2003-based system is running Microsoft Internet Information Services 6.0 (IIS) in Worker Process Isolation Mode ( WPIM), Microsoft Application Center 2000 request forwarding (RF) may not forward requests for brief periods of time and may then resume functioning.

CAUSE

The ISAPI filter portion of RF requires several seconds to initialize.

When IIS 6.0 is run in WPIM, ISAPI filters are loaded only when a request for a site comes in and a worker process is started. Until the initialization is complete, the RF filter only passes the requests to the local host, although you expect the requests to be forwarded.

If the sites that share the worker process are all inactive for a while, RF will be unloaded. Therefore, the problem may recur when the next request for the site is received.

RESOLUTION

To resolve this problem, set IIS 6 to run in IIS 5.0 isolation mode.

WORKAROUND

To work around this problem, configure the worker processes to not be recycled for all application pools that contain sites that require RF. This will minimize the number of times that the RF filter is loaded.

STATUS

This behavior is by design.

REFERENCES

For more information about Worker Process Isolation Mode and IIS 5.0 Isolation Mode, visit the following TechNet Web site:

Modification Type:MinorLast Reviewed:6/22/2006
Keywords:kbprb KB820456 kbAudDeveloper