[erlang-questions] Problem with io monitor - a bug?

Álvaro <>
Fri Nov 30 13:57:18 CET 2012


Dear all,

Every time I run this simple code, my program gets stuck:

> Pid = spawn (moduleName,myread,["hello"]).

where:

myread(Prompt)->
    try
      Result = io:read(Prompt),
      io:format("Res: ~p~n",[Result]),
    catch
    A:B->
        io:format("Read error: ~p:~p~n",[A,B]),
        false
    end.


if I check the status of the process:

> erlang:process_info(Pid).

[{current_function,{io,wait_io_mon_reply,2}},
 {initial_call,{default_environment,myread,1}},
 {status,waiting},
 {message_queue_len,0},
 {messages,[]},
 {links,[]},
 {dictionary,[]},
 {trap_exit,false},
 {error_handler,error_handler},
 {priority,normal},
 {group_leader,<0.25.0>},
 {total_heap_size,233},
 {heap_size,233},
 {stack_size,7},
 {reductions,28},
 {garbage_collection,[{min_bin_vheap_size,46368},
                      {min_heap_size,233},
                      {fullsweep_after,65535},
                      {minor_gcs,0}]},
 {suspending,[]}]


It seems to be stuck in the function io:wait_io_mon_reply/2 (surfing
through io.erl I found that this function waits for a response from the
process managing the io ). This process is not answering, hence my code
stops working.
I've checked that the "group_leader()" once I spawn the reading process is
the same used by my shell.

Any ideas on how to deal with it?

Regards,
Álvaro
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