Re: dup(0) fails on Ubuntu 20.04 and macOS 10.15 with 13.0

On 05.10.20 13:22, Mario Emmenlauer wrote:
> I've used PostgreSQL since version 9.x successfully on Linux, macOS
> and Windows. Today I've upgraded from 12.3 to 13.0 and suddenly I can
> not start the server any more on Ubuntu 20.04 (inside Docker on Ubuntu
> 18.04) and on macOS 10.15.
>
> I get reproducibly the error:
> 2020-10-05 11:48:19.720 CEST [84731] WARNING: dup(0) failed after 0 successes: Bad file descriptor
> 2020-10-05 11:48:19.720 CEST [84731] FATAL: insufficient file descriptors available to start server process
> 2020-10-05 11:48:19.720 CEST [84731] DETAIL: System allows 0, we need at least 58.
> 2020-10-05 11:48:19.720 CEST [84731] LOG: database system is shut down
>
> What makes this quite curious is that everything continues to work on
> Ubuntu 18.04, and Windows with Visual Studio 2019.
>
> I compile postgreSQL myself from source, but there are no patches or
> tweaks involved (that I could think relevant for this problem).
>
> I've searched for the particular error and understand that it is usually
> caused by system limits on new files(?) But in my case, the failing
> setups are relatively modern, powerful CI test machines, with virtually
> no load at the time of test.
>
> On Linux Ubuntu 20.04, `ulimit -n` shows `1048576` which seems also
> relatively high (but must be the default, not changed by me).
>
> Does this problem mean anything to anyone? I'm completely lost where
> to go from here, or what to try next :-( Help would be greatly
> appreciated!

I've just regression-tested 12.4 for the above problem, and I can now
isolate that 12.3 and 12.4 do _not_ give me above problem whereas 13.0
_does_ give me above problem. I tried also to isolate commits that may
be related, but could not find anything useful :-(

Help would be greatly appreciated!

All the best,

Mario Emmenlauer