Subj : Re: Deadlock theorem
To   : comp.programming.threads
From : David Schwartz
Date : Wed May 04 2005 12:31 pm


"Uenal Mutlu" <520001085531-0001@t-online.de> wrote in message 
news:d5ati9$a9j$05$1@news.t-online.com...
> "David Schwartz" wrote

>>     Nope, this code is still illegal by your current rules. There are two
>> possibilities:
>>
>>     1) IsEnd acquires and releases a lock. In this case, your rule 'd' is
>> violated.
>
> Hmm. rule d is there to permit exactly this situation. How can it violate 
> it?

    At this point, I don't think there's any difference between your 
algorithm and just having a lock hierarchy (a specified order in which locks 
must be acquired).

    At times you add additional restrictions, but when they're limitations 
are pointed out, you deny that you actually impose them. At times you grant 
additional abilities, but when it's pointed out that they lead to deadlock, 
you change the rules so they go away.

    So you are saying nothing more than "all threads must acquire locks in 
the same order".

    DS

.