Re: Very frequent "Too many clients" eventually crashes postmaster

On 5/3/20 7:28 AM, Abraham, Danny wrote:
> Is there a way to eliminate postmaster crash/core ?
>
> A surge in short-term connections eventually crashes PG on "no free slots in PMChildFlags array".
>
> Happens on AIX 7.2
>
> =>grep "2020-05-02 08:16" * | grep clients | wc -l
> 0
> =>grep "2020-05-02 08:17" * | grep clients | wc -l
> 0
> =>grep "2020-05-02 08:18" * | grep clients | wc -l
> 309
> =>grep "2020-05-02 08:19" * | grep clients | wc -l
> 603
> =>grep "2020-05-02 08:20" * | grep clients | wc -l
> 288
> =>grep "2020-05-02 08:21" * | grep clients | wc -l
> 230
>
> 2020-05-02 08:21:27.653 CDTFATAL: no free slots in PMChildFlags array
>

Well:

backend/storage/ipc/pmsignal.c
/* Out of slots ... should never happen, else postmaster.c messed up */
elog(FATAL, "no free slots in PMChildFlags array");
return 0; /* keep
compiler quiet */

So:

1) What are your connection settings?

2) What is generating the client traffic?

3) Is there a pooler in front of the server?

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com