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Thread: concurrency control docs error

concurrency control docs error

From
Neil Conway
Date:
The docs on concurrency control & deadlocks (User's Guide, 9.3.3, CVS
docs) state the following:

  Use of explicit locking can cause deadlocks, wherein two (or more)
  transactions each hold locks that the other wants.

This isn't completely true, as deadlocks can occur in applications
that don't use explicit 'LOCK' statements.

Can someone suggest a better way to phrase the intent of that
statement?

Cheers,

Neil

--
Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC

Re: concurrency control docs error

From
Bruce Momjian
Date:
Neil Conway wrote:
> The docs on concurrency control & deadlocks (User's Guide, 9.3.3, CVS
> docs) state the following:
>
>   Use of explicit locking can cause deadlocks, wherein two (or more)
>   transactions each hold locks that the other wants.
>
> This isn't completely true, as deadlocks can occur in applications
> that don't use explicit 'LOCK' statements.
>
> Can someone suggest a better way to phrase the intent of that
> statement?

But it isn't saying there aren't other deadlock cases, just that
explicit locks tend to cause them more frequently.  You can add "Often"
to the front of the sentence.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
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Re: concurrency control docs error

From
Neil Conway
Date:
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> But it isn't saying there aren't other deadlock cases, just that
> explicit locks tend to cause them more frequently.

Well, it doesn't refer to "frequently", or "more often". It just says:

        Doing x can lead to y.

While that statement doesn't imply anything about other things that
can lead to y, a lot of people will take that for granted --
especially if the docs don't mention anything else that might produce
y.

I'll write up something and send it to -patches...

Cheers,

Neil

--
Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC

Re: concurrency control docs error

From
Thomas Lockhart
Date:
Try something like:

Explicit locks can increase the likelyhood of deadlock conditions...

                  - Thomas