Erlang Advocacy and kill -kill

Gordon Guthrie, BTP, BT, SE <>
Tue Jan 20 10:45:07 CET 2004


Folks

I am trying to do a spot of Erlang advocacy. I want to show how you can
start a distributed app across two machines, kill one and then have the
other take over.

However, I want to do it on a laptop as I have to go visiting with it.

I have written a simple app with a top supervisor, a single supervisor under
it which can starts a worker.

I deploy this app to two nodes, 'aardvark' and 'badger' which I start with
batch files (boot scripts will come later) which reference .config files.
These 4 files are shown below:

*********start of start_aardvark ******************

#! /bin/bash
cd /opt/erlang_apps/swarm
erl -s toolbar -sname aardvark -config
/opt/erlang_apps/swarm/aardvark.config -heart

*********end of start_aardvark ********************

*********start of start_badger*********************

#! /bin/bash
cd /opt/erlang_apps/swarm
erl -s toolbar -sname badger -config /opt/erlang_apps/swarm/badger.config
-heart

*********end of start_badger***********************

*********start of aardvark.config******************

[{kernel,
  [{distributed, [{swarm, 5000, [,
{}]}]},
   {sync_nodes_manadatory, []},
   {sync_nodes_timeout, 5000}
  ]
 }
].

*********end of aardvark.config********************

*********start of badger.config********************

[{kernel,
  [{distributed, [{swarm, 5000, [,
{}]}]},
   {sync_nodes_manadatory, []},
   {sync_nodes_timeout, 5000}
  ]
 }
].

*********end of badger.config**********************

So far so good, the two nodes start up, I do application:start(swarm) on
both of them, the application starts on one of them, but not the other.

In order to demonstrate the magic of Erlang I now want to kill the node that
has the app on it and watch the app migrate over, and the node to restart -
kill is our friend. However running 'kill <erlang node pid>' or 'kill -kill
<erlang node pid>' will kill the node but it doesn't failover. I suspect
that this is because Erlang knows I am cheating, and is behaving gracefully.

Have tried 'man murder' but no joy ;-> How can I really slaughter the node
to make sure it fails over (or having I got something wrong in my configs?).

TIA

Gordon

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