Fix Default Port(40000) Busy on Phoenix

If you have problem experienced when you run phoenix server and got error like this [error] Failed to start Ranch listener CoWall.Endpoint.HTTP in :ranch_tcp:listen([port: 4000]) for reason :eaddrinuse (address already in use) . It’s mean that, the default port(4000) has reserved with another process, so you need to release it or use another port.

If you want to known which process is listening on this port You can use this linux cmd lsof -i :4000 to find out more, See this article for examples: http://www.cyberciti.biz/faq/what-process-has-open-linux-port/. Below is the example one.

(erlang-1802)[yrsdi@mac co_wall]$ lsof -i :4000
COMMAND    PID  USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
Google     274 yrsdi  103u  IPv4 0xa174d9f2406034c5      0t0  TCP localhost:54543->localhost:terabase (ESTABLISHED)
beam.smp  7640 yrsdi   20u  IPv4 0xa174d9f2438e60e5      0t0  TCP *:terabase (LISTEN)
beam.smp  7640 yrsdi   25u  IPv4 0xa174d9f2443e7bcd      0t0  TCP localhost:terabase->localhost:54543 (ESTABLISHED)

Use another port

$ PORT=4001 mix phoenix.server

or release it

$ kill -9 <PID>