We used yaws server with embedded mode and the server can be started to process some requests.
HAProxy is used in front end to monitor yaws cluster nodes and receive/dispatch new HTTP webpage/websocket connections.

yaws node will be stucked suddenly and can not receive any new HTTP connection.

We tried to use observer_cli to check the erlang VM node and found the stucked node:

1. yaws_server process stucked a Messsage: [{inet_async, #Port<0.14205>, 4242, {ok, #Port<0.17083>}}] the Message is not processed and flushed
2. the function call is yaws_server:acceptor0/2 , Function: prim_inet:accept0/2

We had tested yaws version 2.0.6, 2.0.9 and tried to change the erlang version 20, 25.
The problem always happened randomly.