Okay, I looked at the code again and I can't see anything wrong
conceptually. It follows libpq semantics which I remember to have grabbed
from the documentation:
results = PQexec(pset->db, query);
/* do something with result */
if (PQstatus(pset->db) == CONNECTION_BAD){ fputs("The connection to the server was lost. Attempting reset: ",
stderr); PQreset(pset->db); if (PQstatus(pset->db) == CONNECTION_BAD) { fputs("Failed.\n", stderr);
PQfinish(pset->db); PQclear(results); pset->db = NULL; return false; } else
fputs("Succeeded.\n",stderr);}
If you can still reproduce this somehow, I'd like to know where it hangs
and/or what the output was.
On 1999-12-25, Tom Lane mentioned:
> The new psql automatically tries to reconnect if the backend disconnects
> unexpectedly. This feature strikes me as ill-conceived; furthermore
> it appears to be buggy.
>
> It's ill-conceived because:
> (1) under WAL, following a backend crash the postmaster is going to be
> spending a few seconds reinitializing; an immediate reconnect attempt
> is almost guaranteed to fail.
Then rip out PQreset. It's not psql's job to make these kinds of
decisions.
> (2) if I'm running an SQL script, I think it's extremely foolhardy
> to press on with executing the script as though nothing had happened.
> A backend crash is not an event to be lightly ignored.
Then rip out PQreset. To quote from the docs:
"This function will close the connection to the backend and attempt to
reestablish a new connection to the same postmaster, using all the same
parameters previously used. This may be useful for error recovery if a
working connection is lost."
I don't know all the possible ways a backend can go down, but one of them
might be a short network failure. In that case attempting a reset might be
the reasonable thing to do. Again, this should be addressed at the libpq
level.
>
> It's buggy because: it doesn't work reliably. While poking at the
> backend's problems with oversize btree index entries, I saw psql claim
> it had successfully reconnected, and then go into a catatonic state.
Look at the above code; seems like a libpq problem.
> It wouldn't give me a new command prompt (not even with ^C), wouldn't
> exit with ^D, and had to be killed from another shell window.
>
> This behavior doesn't seem to happen for every crash, but I'm not
> really interested in trying to debug it. I think the "feature"
I am. :)
> ought to be ripped out.
--
Peter Eisentraut Sernanders väg 10:115
peter_e@gmx.net 75262 Uppsala
http://yi.org/peter-e/ Sweden
