concurrency control docs error

Started by Neil Conwayover 23 years ago4 messagesdocs
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#1Neil Conway
neilc@samurai.com

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

#2Bruce Momjian
bruce@momjian.us
In reply to: Neil Conway (#1)
Re: concurrency control docs error

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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#3Neil Conway
neilc@samurai.com
In reply to: Bruce Momjian (#2)
Re: concurrency control docs error

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

#4Thomas Lockhart
lockhart@fourpalms.org
In reply to: Bruce Momjian (#2)
Re: concurrency control docs error

Try something like:

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

- Thomas