From: Kevin Smith <kevinbsmith@...>
Date: 2001-08-25T10:59:24+09:00
Subject: [ruby-talk:20343] Re: New Windows InstallShield version of Ruby

> That hasn't been our experience with the Cygwin DLL. If
> (for example)
> you're running a bash shell that uses one version of the
> DLL,
> attempting to run Ruby in a DOS window with another
> cygwin DLL
> fails. Kill the bash shell, and the Ruby program works.
> Even through
> there are two DLLs in two different paths, the fact that
> one is loaded
> seems to prevent another from being loaded. Perhaps
> windows can only
> load one DLL of a given name at a time?

I've been out of the Windows internals game for a while,
but I believe this is left over from the 16-bit days, and
I've heard it will be fixed in Windows XP. 

"Modules", as they refer to DLL's and EXE's, have a short
name that is used internally. If that name already exists
in memory, the copy in memory is reused, even if the _path_
to load that module is different. Which is exactly what you
describe.

The other post referred to the possibility that the DLL was
remaining in memory for some time after the last app using
it had unloaded. Someone said this was impossible, but I
find it plausible. Especially if the app being closed
closes its window early, and does some final processing
before actually terminating.

I can also believe, but have no specific knowlege, that
Windows might take its time unloading DLL's, so the
original poster may have been correct.

We've exhausted my knowlege (and then some), so I'll duck
out now.

Kevin

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