From: MenTaLguY <mental@...>
Date: 2006-11-12T06:52:09+09:00
Subject: Re: fast mutexes for 1.8?


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On Wed, 2006-11-08 at 17:07 +0900, Joel VanderWerf wrote:
> I've been complaining about this for *years*.
>=20
> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/61918
> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/219585
>=20
> A suggested fix (which has been stress tested as part of the fsdb=20
> project) is at:
>=20
> http://www.rubygarden.org/ruby?ForkableMutex

Hmm.  Having looked into this, I'm not sure breaking the lock at fork is
the right thing to do.  The reason is that if fork "kills" a thread
while it is holding a lock, you have no idea what state the data the
lock protects is in.

As far as I can tell, the only 100% reliable approach is to quiesce all
threads which might potentially hold locks before forking.

-mental

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