Subj : Re: Improving read-write lock
To   : comp.programming.threads
From : Rob
Date : Thu Feb 17 2005 09:37 am

Joe Seigh wrote:
> On Wed, 16 Feb 2005 18:21:28 +0100, Marcin 'Qrczak' Kowalczyk 
> <qrczak@knm.org.pl> wrote:
> 
>> "Joe Seigh" <jseigh_01@xemaps.com> writes:
>>
>>>> It's not a perfect situation of course, because only one ReadPromotable
>>>> lock exists.
>>>
>>>
>>> More than one promotable read lock can exist.  It just has to stay 
>>> blocked
>>> until any pior promotable read locks have completed their write access.
>>
>>
>> No, because if two threads holding promotable read locks try to
>> promote them, they will deadlock.
> 
> 
> I didn't say that two threads could hold a promotable read lock at the same
> time.  But there can be more than one outstanding request for a promotable
> read lock at the same time.  They just stay blocked until prior write 
> accesses
> have completed.

I think we mean the same thing, but just have a different idea about 
when a lock exists.

.