Re: ERROR: too many dynamic shared memory segments

On Wed, Jan 29, 2020 at 11:53 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> On Wed, Jan 29, 2020 at 10:37 PM Nicola Contu <nicola.contu@gmail.com> wrote:
> > This is the error on postgres log of the segmentation fault :
> >
> > 2020-01-21 14:20:29 GMT [] [42222]: [108-1] db=,user= LOG:  server process (PID 2042) was terminated by signal 11: Segmentation fault
> > 2020-01-21 14:20:29 GMT [] [42222]: [109-1] db=,user= DETAIL:  Failed process was running: select pid from pg_stat_activity where query ilike 'REFRESH MATERIALIZED VIEW CONCURRENTLY matview_vrs_request_stats'
> > 2020-01-21 14:20:29 GMT [] [42222]: [110-1] db=,user= LOG:  terminating any other active server processes

> That gave me an idea...  I hacked my copy of PostgreSQL to flip a coin
> to decide whether to pretend there are no slots free (see below), and
> I managed to make it crash in the regression tests when doing a
> parallel index build.  It's late here now, but I'll look into that
> tomorrow.  It's possible that the parallel index code needs to learn
> to cope with that.

Hi Nicola,

Without more information I can't know if I found the same bug you
experienced, but I think it's likely.  I have committed a fix for
that, which will be available in the next release (mid-February).

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=74618e77b43cfce670b4725d5b9a300a2afd12d1