<div dir="ltr">Hi Michael,<div><br></div><div>I think that the child spec is kept in the supervisor so that one is allowed to do supervisor:restart_child/2. This has been the behavior at least as far back as the git repository goes. And given that the text was changed as far back as OTP-R8B, I don't think that the old documentation is a reason for changing this behavior. </div><div><br></div><div>Regards </div><div>/siri</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2015-07-10 3:53 GMT+02:00 Michael Truog <span dir="ltr"><<a href="mailto:mjtruog@gmail.com" target="_blank">mjtruog@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<tt>Hi,</tt><tt><br>
</tt><tt><br>
</tt><tt>I have noticed that when the supervisor has a child process
with the childspec restart set to transient, and the process </tt><tt>terminates
in a way that is not abnormal, the childspec remains within the
supervisor. This appears to be an error based on old
documentation: "</tt><tt>When a </tt><code>temporary</code><tt>
child dies for any reason or a </tt><code>transient</code><tt>
child dies normally, the child is removed from the supervisor."
(<a href="http://www.erlang.org/documentation/doc-4.8.2/lib/stdlib-1.6.1/doc/html/supervisor.html" target="_blank">http://www.erlang.org/documentation/doc-4.8.2/lib/stdlib-1.6.1/doc/html/supervisor.html</a>).
The new documentation states: "</tt><tt>a </tt><tt><span>transient</span></tt><tt> child process will be
restarted only if it terminates abnormally, i.e. with another exit
reason than </tt><tt><span>normal</span></tt><tt>, </tt><tt><span>shutdown</span></tt><tt> or </tt><tt><span>{shutdown,Term}"
(<a href="http://www.erlang.org/doc/man/supervisor.html" target="_blank">http://www.erlang.org/doc/man/supervisor.html</a>), and this
statement is true with the current supervisor code.<br>
<br>
Is it an error that transient processes that terminate in a way
that is not abnormal do not get removed from the supervisor? I
think it is, but I am not sure if this was accepted legacy
behavior that the documentation didn't want to contradict. I
have an example below with output:<br>
<br>
-module(test).<br>
-behaviour(supervisor).<br>
-export([start_link/0, test_child/0, test/0, init/1]).<br>
start_link() -><br>
supervisor:start_link({local, ?MODULE}, ?MODULE, []).<br>
test_child() -><br>
{ok, erlang:spawn_link(fun() -> erlang:exit(normal)
end)}.<br>
test() -><br>
ChildSpec = {test, {test, test_child, []}, transient, 2000,
worker, []},<br>
supervisor:start_child(?MODULE, ChildSpec).<br>
init([]) -><br>
{ok, {{one_for_one, 5, 300}, []}}.<br>
<br>
<br>
Erlang/OTP 18 [erts-7.0] [source] [64-bit] [smp:2:2] [ds:2:2:10]
[async-threads:10] [kernel-poll:false]<br>
<br>
Eshell V7.0 (abort with ^G)<br>
1> {ok, Sup} = test:start_link().<br>
{ok,<0.35.0>}<br>
2> erlang:unlink(Sup).<br>
true<br>
3> {ok, P} = test:test().<br>
{ok,<0.38.0>}<br>
4> erlang:is_process_alive(P).<br>
false<br>
5> supervisor:which_children(test).<br>
[{test,undefined,worker,[]}]<br>
6> test:test().<br>
{error,already_present}<br>
<br>
Isn't keeping the entry in the supervisor, after a termination
that is not abnormal, an error?<br>
</span></tt><tt><span><br>
Thanks,<br>
Michael<br>
</span></tt>
</div>
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<br></blockquote></div><br></div>