FastCGI ISAPI 1.5 Beta for WinXP and Win2K3

IIS team today released FastCGI ISAPI 1.5 Beta for WinXP and Win2K3 which has some very nice additions to existing FastCGI ISAPI functionality. Following additions have been made to FastCGI ISAPI 1.0.

1. Few features we added to FastCGI module in IIS 7.5 have been added to FastCGI ISAPI 1.5 as well. These include MonitorChangesTo, StderrMode and Real-time tuning. Read more about these here.

Few customers complained about IIS terminating the FastCGI processes abruptly (on running into IdleTimeout, InstanceMax etc) without giving them a chance to run cleanup code in the FastCGI application. In FastCGI ISAPI 1.5, we have added ability to get a signal from IIS whenever we are about to terminate a child process. To enable this, you need to set SignalBeforeTerminateSeconds property in fcgiext.ini to greater than 0. When this functionality is enabled, IIS will create an inheritable event and pass its handle value to child process as value of _FCGI_SHUTDOWN_EVENT_ environment variable. If FastCGI ISAPI ever encounters a situation (like worker process shutting down, fcgiext.ini changed, file being monitored changed etc) and is required to terminate the child process, it will first signal this event and wait for a maximum of SignalBeforeTerminateSeconds for process to terminate on its own. On detecting event being signaled, child processes can terminate themselves cleanly. If child process are still alive after the wait period, IIS will forcibly terminate them.

Name of the named pipe through which communication with FastCGI process is taking place is communicated as value of _FCGI_X_PIPE_ environment variable.

4. Many customers faced trouble with FastCGI 1.0 because they accidently added some invalid configuration to fcgiext.ini and couldn’t decipher the cryptic error message they got from FastCGI ISAPI. In this release, if we see an invalid property present or invalid value of an enum type property, we exactly tell you what’s wrong in fcgiext.ini and where the error is.

5. FastCGI 1.0 had very strict checking on validity of response headers. We got bunch of reports from customers who complained about this difference of behavior compared to other web servers. In this release, we have removed these checks. If we find an invalid response header, we silently drop it from the response. This behavior matches behavior of other web servers.

6. Customers easily ran into ActivityTimeout especially while running install.php code of popular PHP applications. So we have changed default value of ActivityTimeout from 30 seconds to 70 seconds.

Below are the download links to FastCGI ISAPI 1.5 Beta. If you are using WebPI, FastCGI 1.5 is available under “what’s new” section. You can upgrade from FastCGI ISAPI 1.0 to FastCGI ISAPI 1.5 Beta or do a fresh install today. If you any feedback or trouble using FastCGI ISAPI 1.5, please report it on forums.

X86 –

X64 –


We also worked with Mike from Coast Research who fixed many issues in libfcgi.dll. Also he made changes to libfcgi.dll to make it handle SIGTERM properly using SignalBeforeTerminate functionality we added to FastCGI. Mike kindly released updated libfcgi (called libfcgi2.dll) so that others can now write a FastCGI application with much less pain. You can download libfcgi2.dll from here. Mike has published samples and documentation on how to use libfcgi2.dll on Complete white paper on additions to libfcgi2.dll can be found here.



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