Hello Victor, On Wed, 10 Feb 2021 at 16:55, Victor Sudakov <[email protected]> wrote: > > I can even phrase my question in simpler terms. What happens if the sum > total of all servers' maxconns in a backend is less than the maxconn > value in the frontend pointing to the said backend?
Queueing for "timeout queue" amount of time, and then return 503 error (and this really is desirable as opposed to hitting maxconn on a frontend or even worse, global maxconn, because a few milliseconds of delay do not hurt and returning a proper HTTP error in distress is way better then some obscure connection timeout). See: timeout queue https://cbonte.github.io/haproxy-dconv/2.2/configuration.html#4.2-timeout%20queue maxconn https://cbonte.github.io/haproxy-dconv/2.2/configuration.html#5.2-maxconn I really suggest you ignore minconn and fullconn, and focus on maxconn instead. The latter is a must-have (and must-understand). Really maxconn (global, frontend and per server ) is the single most important performance knob in haproxy. Lukas
