Date: Tue, 29 Jan 2002 10:28:04 -0600
From: "Ross J. Reedstrom" <reedstrm@rice.edu>
To: mlw <markw@mohawksoft.com>
Cc: Hannu Krosing <hannu@tm.ee>, Justin Clift <justin@postgresql.org>,
	Tom Lane <tgl@sss.pgh.pa.us>,
	Zeugswetter Andreas SB SD <ZeugswetterA@spardat.at>,
	Vince Vielhaber <vev@michvhf.com>, pgsql-hackers@postgresql.org
Subject: Re: sequence indexes
Message-ID: <20020129162804.GA1525@rice.edu>
Mail-Followup-To: "Ross J. Reedstrom" <reedstrm@ece.rice.edu>,
	mlw <markw@mohawksoft.com>, Hannu Krosing <hannu@tm.ee>,
	Justin Clift <justin@postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>,
	Zeugswetter Andreas SB SD <ZeugswetterA@spardat.at>,
	Vince Vielhaber <vev@michvhf.com>, pgsql-hackers@postgresql.org
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	<3C569908.2D7254EC@mohawksoft.com>
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On Tue, Jan 29, 2002 at 07:43:52AM -0500, mlw wrote:
> Hannu Krosing wrote:
> > 
> > mlw wrote:
> > 
> > One must be very careful not to introduce reverse priority problems -
> > i.e. a
> > lower priority process locking some resource and then not letting go
> > while
> > higher priority processes are blocked from running due to needing that
> > lock.
> I understand that, hmm. I wonder if the lock code could boost the priority of a
> process which owns a lock.
>

The classic approach to solving priority inversion is to allow for
priority inheritance: that is, the low-priority process stays low
priority, even when it locks a resource, until there is contention for
that resource from a higher priority process: then it inherits the higher
priority of the waiting process.

Ross