Re: Printing backtrace of postgres processes

On Sat, Jan 16, 2021 at 1:40 AM Andres Freund <andres@anarazel.de> wrote:
>
> On 2021-01-15 09:53:05 +0100, Peter Eisentraut wrote:
> > On 2020-12-08 10:38, vignesh C wrote:
> > > I have implemented printing of backtrace based on handling it in
> > > CHECK_FOR_INTERRUPTS. This patch also includes the change to allow
> > > getting backtrace of any particular process based on the suggestions.
> > > Attached patch has the implementation for the same.
> > > Thoughts?
> >
> > Are we willing to use up a signal for this?
>
> Why is a full signal needed? Seems the procsignal infrastructure should
> suffice?

Most of the processes have access to ProcSignal, for these processes
printing of callstack signal was handled by using ProcSignal. Pgstat
process & syslogger process do not have access to ProcSignal,
multiplexing with SIGUSR1 is not possible for these processes. So I
handled the printing of callstack for pgstat process & syslogger using
the SIGUSR2 signal.
This is because shared memory is detached before pgstat & syslogger
process is started by using the below:
/* Drop our connection to postmaster's shared memory, as well */
dsm_detach_all();
PGSharedMemoryDetach();

Regards,
Vignesh
EnterpriseDB: http://www.enterprisedb.com