[Spread-users] Circular token over spread: 2 seconds lap time?

[Ryan Caudy]

One thing to try is removing the localhost entry in your spread
segment... this entry is only legal if you have exactly one machine
(usually in segment 127.0.0.255)... doing otherwise can cause the
daemons to behave incorrectly.

The other things to note is that you are using SAFE messages in your
test.  You are measuring more than just the time to send the messages,
but also the time for Spread to make sure that they are ordered, and
stable.  That means that they can be delivered only when the daemon
doing the delivery knows that they (and all messages ordered before
them) have been received at all daemons in the current membership. 
This means that each message's time from send to receipt involves at
least:
<time from sender to daemon> + 1  1/3 <daemon token rotation> (to
ensure stability) + <time from daemon to receiver>.

Of course, this shouldn't cause performance problems like you are
describing, but it could compound other problems (like the localhost
one I mentioned above).  Please let the list know if you continue
having problems after addressing this.

Cheers,
Ryan

On Mon, 26 Jul 2004 14:12:16 +0200, Andreu Moreno i Vendrell
<amoreno at hades.euss.es> wrote:
> Hello,
> 
> We have 2 seconds lap time in a circular token over spread. Do you know what's
> wrong?
> 
> Test description:
> 
> a) 3 computers in an isolated LAN: Machine 1, Machine 2 and Machine 3.
> b) Spread 3.17.2 version installed in every machine.
> c) RedHat 8.0 Linux installed in every machine.
> d) Machine 1: runs a program that joins group "1" and on reception of a
> message it sends a message to group "2".
> e) Machine 2: runs a program that joins group "2" and on reception of a
> message it sends a message to group "3".
> f) Machine 3: runs a program that joins group "3" and on reception of a
> message it sends a message to group "3". This program is the last to be
> executed and also sends a message to group "1" to start the token to
> circulate.
> 
> Results:
> 
> The lap time is about 2 seconds?????
> 
> Thanks,
> 
> Andreu
>

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Ryan W. Caudy
<rcaudy at gmail.com>
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<rcaudy1 at bloomberg.net>
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[Alumnus]
<caudy at cnds.jhu.edu>         
Center for Networking and Distributed Systems
Department of Computer Science
Johns Hopkins University          
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