From: "Guy N. Hurst" <gnhurst@...>
Date: 2002-03-13T14:04:43+09:00
Subject: Re: Some potential RCRs

> Bob Alexander wrote:
...
> The built-in Mutex object should be nestable.
> 
> Acquiring a mutex in nested contexts in the same thread should not cause
> deadlock. It doesn't seem appropriate for a language at Ruby's level to have a
> non-nestable Mutex, and it is a pothole for program errors.
> 


> "Yukihiro Matsumoto" <matz@ruby-lang.org> wrote
...
> > I will take time to investigate it later (I'm not a thread expert).
> > Maybe one of you help me with better implementation.
> 

Sean O'Dell wrote:
...
> I think this definitely needs to change, if that's how it works, or at least
> it should be an option when creating the mutex.  The same context should be
> able to call the same mutex recursively and obtain the lock each time.  Each
> time increasing the mutex' lock count, each release decrementing the mutex
> lock count.
> 
> Often, multiple routines called in the same context will need to lock the
> same mutex to ensure a resource is safely locked.  Since the same context
> isn't likely to step on itself because of a multithreading issue
> 


See http://www.lepton.fr/ruby/rmutex/

Or, you can use a monitor. (See monitor.rb)


Guy N. Hurst