<br><font size=2 face="sans-serif">Hi Felix,</font>
<br>
<br><font size=2 face="sans-serif">Thanks for your answer. However I am
not sure it would prevent 'noconnection' to happen anymore than the previous
solutions? </font>
<br>
<br><font size=2 face="sans-serif">I imagined that there was at least another
process that was concurrently trying to interact with the halted node,
but I did not find any. </font>
<br>
<br><font size=2 face="sans-serif">Maybe, when raising a 'noconnection'
error, specifying its origin could help (ex: "'noconnection' triggered
because process whose PID is P1 (on node N1) tried to send message M to
process whose PID is P2 (on node N2)"). It would be very convenient!</font>
<br>
<br><font size=2 face="sans-serif">Strangely enough, as I had an idle process
on each of the nodes to halt, I made it terminate its node (executing directly
halt() rather than using rpc:cast/3 to trigger the halt()) and 'noconnection'
does not happen anymore. So, in some way, problem solved!<br>
</font>
<br><font size=2 face="sans-serif">Thanks,</font>
<br><font size=2 face="sans-serif">Best regards,</font>
<br><font size=2 face="sans-serif"><br>
Olivier.<br>
---------------------------<br>
Olivier Boudeville<br>
<br>
EDF R&D : 1, avenue du Général de Gaulle, 92140 Clamart, France<br>
Département SINETICS, groupe ASICS (I2A), bureau B-226<br>
Office : +33 1 47 65 59 58 / Mobile : +33 6 16 83 37 22 / Fax : +33 1 47
65 27 13</font>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>fjl@twurst.com</b> </font>
<br><font size=1 face="sans-serif">Envoyé par : erlang-questions-bounces@erlang.org</font>
<p><font size=1 face="sans-serif">25/04/2012 14:26</font>
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<div align=right><font size=1 face="sans-serif">A</font></div>
<td><font size=1 face="sans-serif">erlang-questions@erlang.org</font>
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<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td>
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<td>
<div align=right><font size=1 face="sans-serif">Objet</font></div>
<td><font size=1 face="sans-serif">Re: [erlang-questions] Resisting "noconnection"
/ Remote termination of nodes</font></table>
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<br>
<br><tt><font size=2>Please note that shutdown/1 is not synchronous in
my example.<br>
<br>
On Wed, 25 Apr 2012 14:20:49 +0200, Felix Lange <fjl@twurst.com>
wrote:<br>
<br>
> Hi,<br>
><br>
> I'd suggest using net_kernel:monitor_nodes/1 for this purpose.<br>
><br>
> Example:<br>
><br>
> shutdown(Nodes) -><br>
> spawn_link(fun () -><br>
>
net_kernel:monitor_nodes(true),<br>
>
lists:foreach(fun (Node) -> rpc:cast(Node, <br>
> erlang, halt, []) end, Nodes),<br>
>
wait_dead(Nodes)<br>
> end).<br>
><br>
> wait_dead([]) -><br>
> ok;<br>
> wait_dead([Node | Rest]) -><br>
> receive<br>
>
{nodedown, Node, _} -><br>
> wait_dead(Rest)<br>
> after<br>
> 10000 -><br>
> error_logger:error_report([{shutdown_timeout,
Node}]),<br>
> wait_dead(Rest)<br>
> end.<br>
><br>
> On Tue, 24 Apr 2012 13:52:18 +0200, Olivier BOUDEVILLE <br>
> <olivier.boudeville@edf.fr> wrote:<br>
><br>
>> Hi,<br>
>><br>
>> For a more controlled overall termination of a distributed application,
<br>
>> I<br>
>> try to shutdown synchronously a series of nodes, as properly and
as in<br>
>> parallel as possible, in a non-OTP program. I imagine that using
'[<br>
>> rpc:cast( N, erlang, halt, [] ) || N <- MyTargetNodes ]' and
then <br>
>> waiting<br>
>> for them to be terminated is the best approach for that.<br>
>><br>
>> As I want now these terminations to be synchronous (i.e. I want
my<br>
>> terminate function to return only when all nodes are down for
sure), I<br>
>> used to rely on checking their termination using net_adm:ping/1
(waiting<br>
>> for pong to become pang), but kept on getting (systematically)<br>
>> 'noconnection' errors (exceptions?), which do not seem to be catchable
<br>
>> (at<br>
>> least not with a 'try .. catch T:E ->.. end' clause). This
happens as <br>
>> soon<br>
>> as there is at least one node (which happens to be on the same
host - of<br>
>> course it is not the local node from which that rpc:cast is triggered)
<br>
>> to<br>
>> halt.<br>
>><br>
>> I switched to looping on 'lists:member( Nodename, nodes() )' instead
of<br>
>> ping (in both case with a proper waiting between checks), but
I still <br>
>> get<br>
>> 'noconnection' errors. It looks like 'noconnection' is VM-level?
As<br>
>> expected, commenting-out the rpc:cast/3 never leads to 'noconnection'.<br>
>><br>
>> I feel I would need something like net_kernel:unconnect_node/1.<br>
>><br>
>> My question now: how to deal gracefully with such a synchronous
node<br>
>> shutdown and to resist to the (intended) loss of node(s)?<br>
>><br>
>> Thanks in advance for any hint!<br>
>> Best regards,<br>
>><br>
>> Olivier.<br>
>> ---------------------------<br>
>> Olivier Boudeville<br>
>><br>
>> EDF R&D : 1, avenue du Général de Gaulle, 92140 Clamart, France<br>
>> Département SINETICS, groupe ASICS (I2A), bureau B-226<br>
>> Office : +33 1 47 65 59 58 / Mobile : +33 6 16 83 37 22 / Fax
: +33 1 47<br>
>> 65 27 13<br>
>><br>
>><br>
>><br>
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