From: Caleb Clausen <vikkous@...>
Date: 2007-06-11T05:13:22+09:00
Subject: Re: Synchronized attr_accessor

Nasir Khan wrote:
>     define_method(meth) do |*args|
>       @__ms_lock = Mutex.new unless @__ms_lock
>       @__ms_lock.synchronize do
>         self.send("__nonsync_#{meth}",*args)
>       end
>     end

This still isn't completely thread-safe, I'm afraid. If the lock
doesn't exist yet and two threads both call some synchronized method
on the same object, you've got a race condition. I'd suggest creating
the lock upfront, before the synchronization wrappers are defined....
unfortunately, that makes implementing this idea a bit more
complicated.