Re: [GENERAL] backend dies suddenly after a lot of error messages

> > We have problems with backend processes that close the channel because of
> > palloc() failures. When an INSERT statement fails, the backend reports an
> > error (e.g. `Cannot insert a duplicate key into a unique index') and
> > allocates a few bytes more memory. The next SQL statement that fails
> > causes the backend to allocate more memory again, etc. until we have no
> > more virtual memory left. Is this a bug?
> > We are using postgres 6.4.2 on FreeBSD 2.2.8.
> >
> > It also works with psql:
> >
> > toy=> create table mytable (i integer unique);
> > NOTICE:  CREATE TABLE/UNIQUE will create implicit index mytable_i_key for
> > table mytable
> > CREATE
> > toy=> \q
> >
> > ~ $ # now do a lot of inserts that cause error messages:
> > ~ $ while true; do echo "INSERT INTO mytable VALUES (1);"; done | psql toy
> > INSERT INTO mytable VALUES (1);
> > ERROR:  Cannot insert a duplicate key into a unique index
> > ...quite a lot of these messages
> > INSERT INTO mytable VALUES (1);
> > ERROR:  Cannot insert a duplicate key into a unique index
> > INSERT INTO mytable VALUES (1);
> >
> > pqReadData() -- backend closed the channel unexpectedly.
> >         This probably means the backend terminated abnormally before or
> > while processing the request.
> > We have lost the connection to the backend, so further processing is
> > impossible.  Terminating.
> >
> > Hmm, why does the backend allocate more and more memory with each failed
> > INSERT ?
> > Any clues?

There was a bug in pre-6.5 versions that caused elog failure not to
release their memory.  There is still a small leak for elogs, but it is
only a few bytes.  You should find this is fixed in 6.5.


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