BUG/MEDIUM: listener: make sure the listener never accepts too many conns
We were not checking p->feconn nor the global actconn soon enough. In
older versions this could result in a frontend accepting more connections
than allowed by its maxconn or the global maxconn, exactly N-1 extra
connections where N is the number of threads, provided each of these
threads were running a different listener. But with the lock removal,
it became worse, the excess could be the listener's maxconn multiplied
by the number of threads. Among the nasty side effect was that LI_FULL
could be removed while the limit was still over and in some cases the
polling on the socket was no re-enabled.
This commit takes care of updating and checking p->feconn and the global
actconn *before* processing the connection, so that the listener can be
turned off before accepting the socket if needed. This requires to move
some of the bookkeeping operations form session to listen, which totally
makes sense in this context.
Now the limits are properly respected, even if a listener's maxconn is
over a frontend's. This only applies on top of the listener lock removal
series and doesn't have to be backported.
2 files changed