ERL-1287: SO_REUSEPORT not working with socket backend

[OTP-Maintainer]

Original reporter: juhlig
Affected version: OTP-23.0.2
Fixed in version: OTP-23.1
Component: inet
Migrated from: https://bugs.erlang.org/browse/ERL-1287

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On operating systems that support it, the SO_REUSEPORT option can be used to have multiple sockets listening on the same port. On Linux, for example, this can be enabled with the raw option \{raw, 1, 15, <<1:32>>} (different in other OSes).

 

While this works with the inet backend:
{code:java}
1> gen_tcp:listen(0, [{inet_backend, inet}, {port, 8888}, {raw, 1, 15, <<1:32>>}]).
{ok,#Port<0.8>}
2> gen_tcp:listen(0, [{inet_backend, inet}, {port, 8888}, {raw, 1, 15, <<1:32>>}]).
{ok,#Port<0.9>}
{code}
... it does not work when the socket backend is used:
{code:java}
1> gen_tcp:listen(0, [{inet_backend, socket}, {port, 8888}, {raw, 1, 15, <<1:32>>}]).
{ok,{'$inet',gen_tcp_socket,
             {<0.95.0>,{'$socket',#Ref<0.147054778.119668737.117952>}}}}
2> gen_tcp:listen(0, [{inet_backend, socket}, {port, 8888}, {raw, 1, 15, <<1:32>>}]).
{error,eaddrinuse}
{code}

[OTP-Maintainer]

bmk said:

Hi,

It seems the raw option is not handled properly by gen_tcp when the socket backend is used.

/BMK

 

[OTP-Maintainer]

raimo said:

Fixed for the upcoming maintenance release 23.1 as OTP-16743.