[Info-vax] K-mutex

[Jose Baars]

On Dec 15, 1:50 pm, Pierre <pierre.... at gmail.com> wrote:
> On Dec 15, 1:11 pm, VAXman-  @SendSpamHere.ORG wrote:
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> > In article <99c1d545-9fcb-45ed-b8e0-2e1f053ed... at z17g2000vbe.googlegroups.com>, Jose Baars <peutba... at googlemail.com> writes:
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> > >On Dec 14, 11:18=A0pm, Pierre <pierre.... at gmail.com> wrote:
> > >> On Dec 14, 7:43=A0pm, koeh... at eisner.nospam.encompasserve.org (Bob
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> > >> the easiest way to emulate semaphores with the DLM is to use a lock
> > >> with a value block. this method is not fault-tolerant but neither are
> > >> semaphores (if a process crash before freeing the resource slot, this
> > >> slot may be totally =A0lost).
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> > >Wouldn't the crash of a process holding an EX lock cause the lock to
> > >be released
> > >or freed by a dead lock search?
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> > Process rundown will clean-up locks.  However, if there is some value to
> > the contents of the LVB in the locking scheme, it could still leave your
> > resource stranded.
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> and the SYS$ENQ doc says:
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> The following events can cause the lock value block to become invalid:
> •    If any process holding a protected write or exclusive mode lock
> on a resource
> is terminated abnormally or exits before explicitly dequeuing the lock
> or
> converting it to a lover-level lock mode, the lock value block becomes
> invalid.
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> Pierre

Ok,  I see that in your application this would cause problems.