On Fri, Apr 7, 2023 at 5:34 PM Yurii Rashkovskii <yrashk@gmail.com> wrote: > I'm trying to understand what's wrong with reading port from the pid file (if Postgres writes information there, it's surely so that somebody can read it, otherwise, why write it in the first placd)? The proposed solution uses operating system's functionality to achieve collision-free mechanics with none of the complexity introduced in the commit.
I agree. We don't document the exact format of the postmaster.pid file to my knowledge, but storage.sgml lists all the things it contains, and runtime.sgml documents that the first line contains the postmaster PID, so this is clearly not some totally opaque file that nobody should ever touch. Consequently, I don't agree with Tom's statement that this would be a "a horrid way to find out what was picked." There is some question in my mind about whether this is a feature that we want PostgreSQL to have, and if we do want it, there may be some room for debate about how it's implemented, but I reject the idea that extracting the port number from postmaster.pid is intrinsically a terrible plan. It seems like a perfectly reasonable plan.
I appreciate your support on the pid file concern. What questions do you have about this feature with regard to its desirability and/or implementation? I'd love to learn from your insight and address any of those if I can.
