[Spread-users] Spread Performance

Ryan Caudy caudy at jhu.edu
Tue Apr 27 17:09:13 EDT 2004

[Sorry, I managed to send a draft to the list, by mistake.  I've 
corrected the response below.]

Ryan Caudy wrote:

[Please keep these emails on the spread-users list.]

Answers inlined, again.


William Isley wrote:

 > Ryan,
 > Thank you so much for you help! The only piece that I still need help 
with is how to configure a Spread Daemon for each client.
 > Spread_Segment xxx.yyy.zzz.255:4803 {
 >  hostname1  xxx.yyy.zzz.11
 >  hostname2  xxx.yyy.zzz.12
 >  hostname3  xxx.yyy.zzz.13
 > }
 > What does each "hostname1  xxx.yyy.zzz.11" value represent? A 
different Spread Daemon client on the network? If each client has its 
own Spread Daemon, and the network is a 192.168.1.x network with 
broadcast address, and the local Spread Daemon client on 
the localhost has an IP address of, then would the 
configuration for the local host Spread Daemon look like:

To clarify terminology, when I say "client" I mean any application that 
links with Spread's client library (or uses one of the other client 
interfaces people have developed).  Localhost is the address, 
for all machines (afaik), and is how they can send information to 

 > Spread_Segment {
 >  machine1
 > }

This is fine for a configuration that has only one daemon.  Generally, 
each daemon should have exactly the same spread.conf (and always the 
same segment descriptions).

 > Or is a separate hostname3  xxx.yyy.zzz.13 needed for each Spread 
Daemon on the network?

If I understand your question correctly, yes, one entry of type 
"hostname ip_address" is needed for each *potential* daemon on the 
network.  So, if my cluster has characteristics similar to those you 
described, and I have exactly 6 machines that might run Spread daemons, 
the configuration would be:

Spread_Segment {

Assuming that the hostnames are machine*, the IP addresses are*, and the port you desire to use is 4803.

 > Note that the machines that will use Spread uses DHCP to obtain an IP 
address and can join and leave the network - though not during data 
transmission.  It is a problem if every Spread Daemon on the network 
must be list here because I may not know what Spread Deamon (or clients) 
are available before hand. Is there a way to overcome this?

You will need to list every potential Spread daemon on the network here. 
  It won't be a problem (although you can't have more than 128 daemons 
running at a given time, and I wouldn't recommend letting your system 
get too large for latency reasons).

 > Thank you again for your help,
 > William Isley

Ryan W. Caudy
Center for Networking and Distributed Systems
Department of Computer Science
Johns Hopkins University

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