[erlang-questions] Process unexpectedly locks up

[Sam Bobroff]

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Hi Doug (and the list),

(I'll reply to the questions list)

[...]

> I've received this reply from Sam Bobroff, which indicates
> there is some kind of conflict with "io:wait_io_mon_reply".

I'll add to my previous reply:

I think you have two options:

1. Use the interactive shell (don't use "-noshell" on the command line):

Since you can't use io:get_line(), you could modify the "down" handler
in me_loop() in two places:

* if the down case requires a decision, just print out the options (as
now) and otherwise don't do anything.

* add a handler for a {down, X} message that takes choice X as if it had
been returned from get_user_input() in the old code.

So now you do "me ! down" and get a message that it failed, with your
options, then you do "me ! {down, 1}" to pick one. You never use
get_line() so there is no conflict.

2. Don't use the shell (so *do* use "-noinput"):

Since you're not using the shell, you can't drive the threads using
messages. Instead, have the start() function continue on into an
interactive loop calling get_line() and translating it into up, down or
whatever, messages sent to "me". Then when you want to make a choice you
can just call get_user_input() as you do now.

I don't really think there's a bug (in Erlang) but the documentation for
get_line would certainly be better if it said something about the
interaction between the shell and the io input functions.

Cheers,
Sam.

- -- 
Sam Bobroff | sam@REDACTED | M5 Networks
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