From: "Schmidt, Oliver" <oliv.schmidt@sap.com>
To: "cygwin@cygwin.com" <cygwin@cygwin.com>
Date: Tue, 9 Mar 2010 11:08:22 +0100
Subject: RE: Cygwin 1.7: Concurrency Issue with Shared State Initialization
Message-ID: <B10B50309DC54D45A855FD66F56015F71D07C79605@DEWDFECCR03.wdf.sap.corp>
References: <B10B50309DC54D45A855FD66F56015F71D07C78CAE@DEWDFECCR03.wdf.sap.corp>  <20100308195656.GA17237@ednor.casa.cgf.cx>
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Hi Christopher,

Fist of all thanks for your immediate feedback :-)

>>    /* Initialize installation root dir. */
>>     if (!installation_root[0])
>>       init_installation_root ();

> I'll check in something tonight which attempts to solve this problem.

Thanks in advance.

> It's a somewhat tricky problem because adding a mutex here would slow
> down every invocation of a cygwin program and we don't want to add to
> the "Why is Cygwin so slow???" scenarios if we can help it.

I understand your concern for sure ;-)

Maybe that's the very thing you're thinking about but ... AFAIK a spinlock =
is the usual paradigm in scenarios where one doesn't anticipate contention =
but needs to be aware of it 'just in case'. With InterlockedCompareExchange=
() and Sleep() it should be quite simple to create one that's very efficien=
t in the usual scenario.

Regards, Oliver

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