CODEWITHSUNDEEP
erlangmnesia
vinnitu
vinnitu

Reputation: 4364

erlang node not responding

I received such message in erlang condose at first@localhost node

=ERROR REPORT==== 1-Jan-2011::23:19:28 ===
** Node 'second@localhost' not responding **
** Removing (timedout) connection **

My question is - what is timeout in this case? How much time before causes this event? Howto prevent this "horror"? I can restore\recover to normal work only by restart node... But what is the right way?

Thank you, and Happy New Year!

Upvotes: 4

Views: 1360

Answers (1)

Roberto Aloi
Roberto Aloi

Reputation: 30985

Grepping for the not responding string in the Erlang source code, you can see how the message is generated in the dist_util module in the kernel application (con_loop function).

    {error, not_responding} ->
        error_msg("** Node ~p not responding **~n"
              "** Removing (timedout) connection **~n",
              [Node]),

Within the module, the following documentation is present, explaining the logic behind ticks and not responding nodes:

%%
%% Send a TICK to the other side.
%%
%% This will happen every 15 seconds (by default) 
%% The idea here is that every 15 secs, we write a little 
%% something on the connection if we haven't written anything for 
%% the last 15 secs.
%% This will ensure that nodes that are not responding due to 
%% hardware errors (Or being suspended by means of ^Z) will 
%% be considered to be down. If we do not want to have this  
%% we must start the net_kernel (in erlang) without its 
%% ticker process, In that case this code will never run 

%% And then every 60 seconds we also check the connection and 
%% close it if we havn't received anything on it for the 
%% last 60 secs. If ticked == tick we havn't received anything 
%% on the connection the last 60 secs. 

%% The detection time interval is thus, by default, 45s < DT < 75s 

%% A HIDDEN node is always (if not a pending write) ticked if 
%% we haven't read anything as a hidden node only ticks when it receives 
%% a TICK !!

Hope this helps a bit.

Upvotes: 9

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