aleklisi / cowboy_termiante_exit

Example for cowboy handler terminate fail to execute when client closes connection

cowboy_termiante_exit

This repository is providing minimal counterexample for

"The optional terminate/3 callback will ultimately be called with the reason for the termination of the handler. Cowboy will terminate the process right after this. There is no need to perform any cleanup in this callback."

from

https://ninenines.eu/docs/en/cowboy/2.6/manual/cowboy_handler/

Steps to reproduce

• Setup cowboy with http endpoint and terminate call in handler.
• The terminate call must last for a moment (like 1 second).
• Add calls counters in init/2 and terminate/3 calls.
• Make http request.
• Wait for reply (with status 200) (like 3 second to make sure that terminate/3 call had enough time to execute).
• Assert number of init/2 and terminate/3 calls.

How to run example

rebar3 shell

% trace goes here

eunit:test(issue).

Suspected issue

Add following tracing:

dbg:tracer().
dbg:p(all, c).
dbg:p(all, p).
dbg:tpl(toppage_h, init, x).
dbg:tpl(toppage_h, terminate, x).

Notice that you get:

...
(<0.229.0>) exit {shutdown,{socket_error,closed,'The socket has been closed.'}}
...

More over if you uncomment

...
% process_flag(trap_exit, true),
...

in src/toppage_h.erl the issue will be solved.