Re: PMChildFlags array

> Hi,
>
> Observed below errors in logfile
>
> 2019-09-20 02:00:24.504 UTC,,,99779,,5d73303a.185c3,73,,2019-09-07
> 04:21:14 UTC,,0,FATAL,XX000,"no free slots in PMChildFlags
array",,,,,,,,,""
> 2019-09-20 02:00:24.505 UTC,,,109949,,5d8432b8.1ad7d,1,,2019-09-20
> 02:00:24 UTC,,0,ERROR,58P01,"could not open shared memory segment
> ""/PostgreSQL.2520932"": No such file or directory",,,,,,,,,""
> 2019-09-20 02:00:24.505 UTC,,,109950,,5d8432b8.1ad7e,1,,2019-09-20
> 02:00:24 UTC,,0,ERROR,58P01,"could not open shared memory segment
> ""/PostgreSQL.2520932"": No such file or directory",,,,,,,,,""
>

>Postgres version?

PostgreSQL 10.8

>OS and version?

NAME="Ubuntu"
VERSION="18.04.1 LTS (Bionic Beaver)"

What was the database doing just before the FATAL line?

Postgres was rejecting a bunch of connections from a user who is having a
connection limit set. that was the the FATAL error that i could see in log
file.
FATAL,53300,"too many connections for role ""user_app"""

db=\du user_app
List of roles
Role name | Attributes | Member of
--------------+-------------------------------+--------------------
user_app | No inheritance +| {application_role}
| 100 connections +|
| Password valid until infinity |

> what could be the possible reasons for this to occur and is there any
> chance of database corruption after this event ?

The source(backend/storage/ipc/pmsignal.c ) says:

"/* Out of slots ... should never happen, else postmaster.c messed up */
elog(FATAL, "no free slots in PMChildFlags array");
"

Someone else will need to comment on what 'messed up' could be

On Thu, 3 Oct 2019 at 18:56, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

> On 10/3/19 3:57 AM, bhargav kamineni wrote:
> > Hi,
> >
> > Observed below errors in logfile
> >
> > 2019-09-20 02:00:24.504 UTC,,,99779,,5d73303a.185c3,73,,2019-09-07
> > 04:21:14 UTC,,0,FATAL,XX000,"no free slots in PMChildFlags
> array",,,,,,,,,""
> > 2019-09-20 02:00:24.505 UTC,,,109949,,5d8432b8.1ad7d,1,,2019-09-20
> > 02:00:24 UTC,,0,ERROR,58P01,"could not open shared memory segment
> > ""/PostgreSQL.2520932"": No such file or directory",,,,,,,,,""
> > 2019-09-20 02:00:24.505 UTC,,,109950,,5d8432b8.1ad7e,1,,2019-09-20
> > 02:00:24 UTC,,0,ERROR,58P01,"could not open shared memory segment
> > ""/PostgreSQL.2520932"": No such file or directory",,,,,,,,,""
> >
>
> Postgres version?
>
> OS and version?
>
> What was the database doing just before the FATAL line?
>
> > what could be the possible reasons for this to occur and is there any
> > chance of database corruption after this event ?
>
> The source(backend/storage/ipc/pmsignal.c ) says:
>
> "/* Out of slots ... should never happen, else postmaster.c messed up */
> elog(FATAL, "no free slots in PMChildFlags array");
> "
>
> Someone else will need to comment on what 'messed up' could be.
>
> >
> >
> > Regards,
> > Bhargav
> >
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>