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From Danny Sadinoff <>
Subject mod_fcgid: different instances of the same program
Date Mon, 09 Nov 2009 22:16:07 GMT
Here are two details of mod_fcgid process management that I've just
learned after a long debug session and squinting at the mod_fcgid

1) symlinks & you.
It seems that mod_fcgid identifies fcgid programs by inode and device,
not by filename.  So two fcgid programs invoked by the webserver
along different paths will be counted as the same if the two paths are
hardlinks or softlinks to each other.

2) Virtual hosts
The above item holds true even across virtual hosts.   So while
it's possible to adjust the FcgidInitialEnv items on a per-vhost
basis, this is a recipe for disaster if two vhosts point at the same
fcgi executable, because the resulting processes with potentially
different Environments will be inserted into the same pool.  Once that
occurs, we may expect that a server spawned with config defined in
vhost A will be parcelled out to vhost B.

The Apache httpd 2.3 docs do not address the symlink issue at all, and
the virtual host issue only indirectly.

I'd appreciate it if someone could confirm or deny the above.  If I'm
right, can we add it to the docs?  None of it seems obvious to me.
Apologies in advance if this is the sort of thing that belongs on the
dev list.  I'm happy to throw together a doc patch.

Thanks in advance

P.S. having a lot of trouble getting this message posted to the list.  Not
sure what's up with that.

Danny Sadinoff

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