EAP 7 Undertow/XNIO max-connections behavior changes since EAP 7.0.4

Issue

• The following max-connections and tcp-backlog are configured in http-listener inside undertow subsystem in EAP 7:

  <http-listener name="default" socket-binding="http" redirect-socket="https" max-connections="100" tcp-backlog="100"/>
  

• As far as I tested, the behavior is different after EAP 7.0.4 or later:

  • Until EAP 7.0.3, a new connection which exceeds max-connections is queued in the TCP backlog which size is specified by tcp-backlog.
  • Since EAP 7.0.4, EAP 7 does not queue a new connection which exceeds max-connections but it immediately closes the exceeded connections.

What caused this behavior change?