Subj : Re: Challenge: Multithreading & Synchronization
To   : comp.programming.threads
From : gottlobfrege
Date : Wed May 18 2005 11:20 pm


Uenal Mutlu wrote:
> > >>       // assume all public functions can make calls to each
other,
> > >>       // and also to internal funcs
> > >>
> > >>       void f1(void* Ap = 0)
> > >>         { // uses vJD, vMD
> > >>           Locker L1(vJD.m);       // the order of the locks is
important
> > >>           Locker L2(vMD.m);
> > >>
> > >>           //...
> > >>         }
> > >>
> > >>       void f2(void* Ap = 0)
> > >>         { // uses vMD, vSD
> > >>           Locker L1(vSD.m);
> > >>           Locker L2(vMD.m);
> > >>
> > >>           //...
> > >>         }
> > >>
> > >>       void f3(void* Ap = 0)
> > >>         { // uses vSD, vMD
> > >>           Locker L1(vSD.m);
> > >>           Locker L2(vMD.m);
> > >>
> > >>           //...
> > >>         }


Maybe I'm missing something:

thread 1 calls f1, locks JD, MD...

           thread 2 slips in and calls f2, locks SD, tries to lock MD,
but has to wait on thread 1.

thread 1 continues, and, based on
> > >>       // assume all public functions can make calls to each
other,
let's say f1 calls f3, thus tries to lock SD, but can't because thread
2 has it locked, so waits on thread 2 who is waiting on thread 1...

am I missing something?

Tony

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