Re: slru.c race condition - Mailing list pgsql-hackers

From Chris Browne
Subject Re: slru.c race condition
Date
Msg-id 60oe547zxe.fsf@dba2.int.libertyrms.com
Whole thread Raw
In response to Re: TRAP: FailedAssertion("!((itemid)->lp_flags & 0x01)",  ("Jim Nasby" <jnasby@pervasive.com>)
List pgsql-hackers
alvherre@alvh.no-ip.org (Alvaro Herrera) writes:

> Chris Browne wrote:
>> jnasby@pervasive.com ("Jim C. Nasby") writes:
>> 
>> > On Tue, Nov 01, 2005 at 11:23:55AM -0300, Alvaro Herrera wrote:
>> >> Tom Lane wrote:
>> >> > "Jim C. Nasby" <jnasby@pervasive.com> writes:
>> >> > > AFAIK they're not using subtransactions at all, but I'll check.
>> >> > 
>> >> > Well, yeah, they are ... else you'd never have seen this failure.
>> >> 
>> >> Maybe it's in plpgsql EXCEPTION clauses.
>> >
>> > Err, I forgot they're using Slony, which is probably using savepoints
>> > and/or exceptions.
>> 
>> Slony-I does use exceptions in pretty conventional ways; it does *not*
>> make any use of subtransactions, because it needs to run on PG 7.3 and
>> 7.4 that do not support subtransactions.
>
> Hmm, does it use the BEGIN/EXCEPTION/END construct at all?  Because if
> it does, it won't work on 7.4; and if it doesn't, then it isn't using
> savepoints in 8.0 either.

Ah, then I was misreading that.  

There are instances of RAISE EXCEPTION, which was what I had in mind,
but not of BEGIN/EXCEPTION/END.

There is some logic in 8.x to *detect* the nesting of transactions,
but that's quite another matter.
-- 
output = ("cbbrowne" "@" "acm.org")
http://cbbrowne.com/info/multiplexor.html
"If I  could find  a way to  get [Saddam  Hussein] out of  there, even
putting a  contract out on him,  if the CIA  still did that sort  of a
thing, assuming it ever did, I would be for it."  -- Richard M. Nixon


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