[erlang-questions] gen_udp port leaking after controlling_process(Port, self())

[Max Lapshin]

Open UDP port

$ erl
Erlang R14B02 (erts-5.8.3) [source] [64-bit] [smp:4:4] [rq:4]
[async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.3  (abort with ^G)
1> {ok,Port} = gen_udp:open(9000, [binary]).
{ok,#Port<0.576>}

$ lsof -nP -i|grep beam|grep UDP
beam.smp  10912  max   11u  IPv4 0x089073c4      0t0  UDP *:9000



Simulate error:
2> a=b.
** exception error: no match of right hand side value b

All ports are closed.

$ lsof -nP -i|grep beam|grep UDP
$


Now add controlling_process:

4> {ok,Port} = gen_udp:open(9000, [binary]).
{ok,#Port<0.587>}
5> gen_udp:controlling_process(Port, self()).
ok
6> a=b.
** exception error: no match of right hand side value b

Voila: port is not closed

lsof -nP -i|grep beam|grep UDP
beam.smp  10912  max   11u  IPv4 0x089073c4      0t0  UDP *:9000


Where is it? To which process belongs it now and when will it be closed?