Cygwin 1.7: Concurrency Issue with Shared State Initialization

[Christopher Faylor]

On Tue, Mar 09, 2010 at 12:36:08PM +0100, Corinna Vinschen wrote:
>On Mar  9 11:08, Schmidt, Oliver wrote:
>> 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 efficient in the usual scenario.
>
>Does the below patch fix this for you?

I really do have a patch sitting in my sandbox.  I just forgot to test it
last night.

cgf

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