[erlang-questions] jinterface

Robert Virding <>
Sat Oct 4 16:57:42 CEST 2008


That would be a better solution in the long-run, but it is one which,
unfortunately, I can't help you with.

Robert

2008/10/4 Serge Aleynikov <>

> Ah, I see, this makes sense.  Meanwhile, I looked through the distribution
> sources, ei, and jinterface and see that it's not that difficult to add some
> monitoring support for non-Erlang nodes so that they can monitor Erlang
> pids.  I'll patch otp.net and later ei if I find time this or next
> weekend.
>
> Serge
>
>
> Robert Virding wrote:
>
>> It's not the io server which tries to setup a monitor, but the io module
>> itself. These are two separate but cooperating entities. The io module
>> monitors the io server to make sure that the call will not block if the
>> process dies. The easiest way around this is to do the send/receive to the
>> io serv yourself without a monitor.
>>
>> Robert
>>
>> 2008/10/4 Serge Aleynikov <>
>>
>>  One other "nasty" feature is that any attempt to make an RPC call of
>>> io:format/2 from a Java/.NET node fails with badarg, because io server
>>> tries to set up a monitor to the remote pid and fails miserably...
>>>
>>> Actually I see what's missing in Java/OTP.NET implementation.  These
>>> features are documented here:
>>> http://www.erlang.org/doc/apps/erts/erl_dist_protocol.html#9.7
>>>
>>> Serge
>>>
>>>
>>>
>>> Paul Guyot wrote:
>>>
>>>> Date: Sat, 04 Oct 2008 01:32:55 -0400
>>>>> From: Serge Aleynikov <>
>>>>> Subject: Re: [erlang-questions] jinterface (was: otp.net)
>>>>>
>>>>> I tried a similar test using jinterface to see if it's possible to
>>>>> monitor processes running on a Java node and ran into the same failure.
>>>>>
>>>>> Can anyone explain what's wrong?
>>>>>
>>>>> ()10> {test, } ! {self(), hello}.
>>>>> {<0.45.0>,hello}
>>>>> ()11> f(), {Pid, _} = receive M -> M end.
>>>>> {<5979.1.0>,hello}
>>>>> ()12> erlang:monitor(process, Pid).
>>>>> ** exception error: bad argument
>>>>>      in function  erlang:monitor/2
>>>>>         called as erlang:monitor(process,<5979.1.0>)
>>>>>
>>>> I've seen a comment in stdlib/gen.erl, at line 196, that suggests that
>>>> Java and C nodes are featureweak, and processes in such nodes cannot be
>>>> monitored. Instead, you have to monitor the whole node with
>>>> monitor_node/2. This makes sense because the OTP ei (C library) or
>>>> jinterface do not monitor "processes". Indeed, there is only one pid per
>>>> node, which is the node's pseudo-pid (even if technically, each
>>>> connection can receive messages). I guess you can draw from the code in
>>>> gen.erl if you need to monitor either an erlang process or your java
>>>> process, or just monitor the node if you only need to monitor java
>>>> processes.
>>>>
>>>> Regards,
>>>>
>>>> Paul
>>>>
>>>>
>>>>  _______________________________________________
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>>> 
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>>>
>>>
>>
>
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