Re: Orphaned locks in 7.0?

* Hiroshi Inoue <Inoue@tpf.co.jp> [000515 02:07] wrote:
> > -----Original Message-----
> > From: pgsql-hackers-owner@hub.org [mailto:pgsql-hackers-owner@hub.org]On
> > Behalf Of Alfred Perlstein
> > 
> > Basically I was running two instances of psql, in one I issued:
> > 
> >           one                              two
> > 
> > begin;
> > lock data;  -- some table
> >                                       lock data;^C -- cancel
> >                                       select * from data;^C -- cancel
> > end;
> >                                       
> >                                       lock data;^C -- HUNG then aborted
> > 
> > It's annoying that I can't seem to reproduce this, and I know LOCKs
> > are only to be requested during a transaction, but it did happen.
> >
> 
> Could the following example explain your HUNG problem ?
> 
> Session-1
>     # begin;
>     BEGIN
>     =# lock t;
>     LOCK TABLE
> 
> Session-2
>     =# begin;
>     BEGIN
>     =# lock t; 
>     [blocked] ^C
>     Cancel request sent
>     ERROR:  Query cancel requested while waiting lock
>     reindex=# select * from t;
>     [blocked]
> 
> Session-1
>     =# commit;
>     COMMIT
> 
> Session-2
>     ERROR:  LockRelation: LockAcquire failed
>     =# abort;
>     ROLLBACK
>     =# lock t;
>     [blocked]

That looks pretty much like the sequence of events that lead up to
the problem, the problem is that I was just manually testing out
the way locks work and didn't write down the exact steps I took.

This is probably exactly the right steps though.

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."