On 2020-11-23 17:00, David G. Johnston wrote:
So presently there is no functioning code to prevent two PostgreSQL
instances from using the same socket so long as they do not also use the
same data directory? We only handle the case of an unclean crash -
where the pid and socket are both left behind - having the system tell
the user to remove the pid lock file but then auto-replacing the socket
(I was conflating the behavior with the pid lock file and the socket file).
I would expect that we handle port misconfiguration also, by not
auto-replacing the socket and instead have the existing error message
(with modified hint) remain behind. This provides behavior consistent
with TCP port binding. Or is it the case that we always attempt to bind
the TCP/IP port, regardless of the presence of a socket file, in which
case the failure for port binding does cover the socket situation as
well? If this is the case, pointing that out in [1] and a code comment,
while removing that particular error as "dead code", would work.
We're subject to whatever the kernel behavior is. If the kernel doesn't
report address conflicts for Unix-domain sockets, then we can't do
anything about that. Having an error message ready in case the kernel
does report such an error is not useful if it never does.
--
Peter Eisentraut
2ndQuadrant, an EDB company
https://www.2ndquadrant.com/
