Re: csvlog gets crazy when csv file is not writable

On Mon, Aug 20, 2018 at 03:55:01PM +0200, Alexander Kukushkin wrote:
> If for some reason postgres can't open 'postgresql-%Y-%m-%d.csv' file
> for writing, it gets mad and outputs a few thousands of lines to
> stderr:
>
> 2018-08-20 15:40:46.920 CEST [22069] PANIC:  could not open log file

Ah, this log message could be changed to be simply "could not open
file", the file name offers enough context...

> And so on. ERRORDATA_STACK_SIZE is presented in the output 3963 times
> 
> Sure, it is entirely my fault, that csv file is not writable, but such
> avalanche of PANIC lines is really scary.

Yeah, this is a recursion in logfile_open -> open_csvlogfile.  With
stderr there is a much better effort, where the server just quits with a
FATAL if the log file cannot be opened in SysLogger_Start.  Could this
be an argument for allowing logfile_open() to use write_stderr?  I am
not sure under the hood of the don't-do-that rule.  And we make sure
that log_destination is writable already at early stage, which would
cover any scenarios like a kernel switching the log partition to be
read-only.
--
Michael