Hi, Here are my two cents.
> > I would like to suggest a patch against master (although it may be worth > > backporting it) that makes it possible to listen on any unused port. > > I think this is a bad idea, mainly because this: > > > Instead, with this patch, one can specify `port` as `0` (the "wildcard" > > port) and retrieve the assigned port from postmaster.pid > > is a horrid way to find out what was picked, and yet there could > be no other. What personally I dislike about this approach is the fact that it is not guaranteed to work in the general case. Let's say the test framework started Postgres on a random port. Then the framework started to do something else, building a Docker container for instance. While the framework is busy PostgreSQL crashes (crazy, I know, but not impossible). Both PID and the port will be reused eventually by another process. How soon is the implementation detail of the given OS and its setting. A bullet-proof approach would be (approximately) for the test framework to lease the ports on the given machine, for instance by using a KV value with CAS support like Consul or etcd (or another PostgreSQL instance), as this is done for leader election in distributed systems (so called leader lease). After leasing the port the framework knows no other testing process on the given machine will use it (and also it keeps telling the KV storage that the port is still leased) and specifies it in postgresql.conf as usual. I realize this is a complicated problem to solve in a general case, but it doesn't look like the proposed patch is the right solution for the named problem. -- Best regards, Aleksander Alekseev
