On Mon, Oct 18, 2010 at 10:24 PM, Fujii Masao <masao.fu...@gmail.com> wrote: > I mean, for example, that the server cannot detect the disconnection for > more than 60 seconds even if the user configures the keepalive as follows. > > tcp_keepalives_idle = 10 > tcp_keepalives_interval = 5 > tcp_keepalives_count = 2
Yeah, TCP is not going to detect a broken connection that quickly. I think there's a fundamental impedence mismatch of between the application needs here and the design goals of TCP. TCP is designed to work if at all possible and only generate an error if it's unavoidable. Keepalives were controversial when they were proposed but for the original purpose -- ensuring that long-lived servers didn't leak connections indefinitely -- they serve they work. The point of them was to cover the remaining cases where there was no data in flight and therefore no way to ever detect that the connection was dead. TCP is only going to detect a connection as dead if it has exceeded all the engineering limits of the network. Until then it's still possible it'll come back and having the network layer generate an error when it's possible the connection is still functioning would be bad. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
