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7232677385
Do not remove anymore idle and purgeable connections directly under the "del server" handler. The main objective of this patch is to reduce the amount of work performed under thread isolation. This should improve "del server" scheduling with other haproxy tasks. Another objective is to be able to properly support dynamic servers with QUIC. Indeed, takeover is not yet implemented for this protocol, hence it is not possible to rely on cleanup of idle connections performed by a single thread under "del server" handler. With this change it is not possible anymore to remove a server if there is still idle connections referencing it. To ensure this cannot be performed, srv_check_for_deletion() has been extended to check server counters for idle and idle private connections. Server deletion should still remain a viable procedure, as first it is mandatory to put the targetted server into maintenance. This step forces the cleanup of its existing idle connections. Thanks to a recent change, all finishing connections are also removed immediately instead of becoming idle. In short, this patch transforms idle connections removal from a synchronous to an asynchronous procedure. However, this should remain a steadfast and quick method achievable in less than a second. This patch is considered major as some users may notice this change when removing a server. In particular with the following CLI commands pipeline: "disable server <X>; shutdown sessions server <X>; del server <X>" Server deletion will now probably fail, as idle connections purge cannot be completed immediately. Thus, it is now highly advise to always use a small delay "wait srv-removable" before "del server" to ensure that idle connections purge is executed prior. Along with this change, documentation for "del server" and related "shutdown sessions server" has been refined, in particular to better highlight under what conditions a server can be removed.
