Re: Can we have a new SQL callable function to get Postmaster PID?

On 2/3/21 7:12 AM, Bharath Rupireddy wrote:
> Hi,
>
> Can we have a new function, say pg_postgres_pid(), to return
> postmaster PID similar to pg_backend_pid()? At times, it will be
> difficult to use OS level commands to get the postmaster pid of a
> backend to which it is connected. It's even worse if we have multiple
> postgres server instances running on the same system. I'm not sure
> whether it's safe to expose postmaster pid this way, but it will be
> useful at least for debugging purposes on say Windows or other
> non-Linux platforms where it's a bit difficult to get process id.
> Users can also look at the postmaster.pid file to figure out what's
> the current postmaster pid, if not using OS level commands, but having
> a SQL callable function makes life easier.
>
> The function can look like this:
> Datum
> pg_postgres_pid(PG_FUNCTION_ARGS)
> {
> PG_RETURN_INT32(PostmasterPid);
> }
>
> Thoughts?
>

Curious question - why do you actually need PID of the postmaster? For
debugging, I'd say it's not quite necessary - you can just attach a
debugger to the backend and print the PostmasterPid directly. Or am I
missing something?

regards

--
Tomas Vondra
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