Subj : Re: Deadlock theorem
To   : comp.programming.threads
From : Uenal Mutlu
Date : Mon May 02 2005 12:40 am

"doug" wrote
> 'fraid this is just standard 'semaphore hierarchy'.

Really? Do you have a link to the definition of "semaphore hierarchy" ?


> "Uenal Mutlu" wrote
>
> > Theorem:
> >   a) "There will be no deadlock if the objects are locked in the same
> > order."
> >   b) "Unlocking can be done in any order."
> >
> > Some explanation:
> > "Order" in this context means sequence.
> > The theorem applies equally well to both sequential and parallel
> > processing
> > (ie. threads, tasks, processes, coroutines etc.), and regardless of the
> > number
> > of objects one wishes to lock in any of the parallel running units (aka
> > threads).
> > That is: the objects designated for locking, and the number of them, can
> > be
> > different in each thread; only the locking sequence (order) must be the
> > same in all threads.
> >
> > (If this theorem is new then I would like to give it the name "Mutlu
> > theorem" :-)

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