[Spread-users] New to spread, some questions
rcaudy at gmail.com
Fri Feb 4 19:02:31 EST 2005
Spread daemons in the same segment can communicate via
multicast/broadcast. Spread daemons communicate to their clients
individually, via TCP/IP (for remote or windows connections) or Unix
Domain Sockets for local clients on Unix/Linux machines.
There are efficiency/latency tradeoffs to be made. Every Spread
daemon you add is one more holder for the token, hence increasing the
latency costs for message ordering and guarantees. Every non-local
client, on the other hand, is one more time the messages that need to
be delivered to that client are transmitted on the network. The
overall cost depends on your network architecture, and your
For many basic applications, the recommendation is one Spread daemon
per machine that you'll have clients on. This way, all the clients
can be local to their daemons.
On Fri, 4 Feb 2005 04:05:52 -0800 (PST), pedro smith <und_pep at yahoo.com> wrote:
> Thank you,
> Just so I understand the design better, what is gained by using more than
> one spread daemon? If I have a lan with say 200 processes communicating
> through spread, some on the same machines, how many spread daemons should I
> run and why?
> Ryan Caudy <rcaudy at gmail.com> wrote:
> You seem to understand this correctly. The set of spread daemons
> (identified by hostname/ip address) must be known when the daemons are
> started. The limit of 128 spread daemons (#define'd as
> MAX_PROCS_RING) is fixed at compile-time -- you might be able to make
> some changes to this, but I'm not sure if anyone has done so, and
> there may be complications that I can't think of off the top of my
> head. As far as I know, there aren't currently plans to change
> Spread's functionality in these respects.
> One thing to consider is that the 128 limit is a limit of the number
> of daemons -- the number of clients is a large multiple of this.
> Also, you can run more than one Spread network on an overlapping set
> of machines -- they simply must use different ports, or different
> multicast/broadcast addresses.
> On Thu, 3 Feb 2005 18:46:54 -0800 (PST), pedro smith wrote:
> > Hi there,
> > I just found Spread and I am very interested in learning more about its
> > capabilities. I am considering using something like spread in a financial
> > system. However I am worried about two issues. First, it seems that the
> > of machines participating in a spread segment must be know at system boot
> > time. Is this right? Would I have to reinitialize every spread daemon in
> > system to add a new machine? Second, do I understand correctly that there
> > a hard limit of 128 machines in a spread network? If so, are there any
> > around this limit, perhaps by bridging separate networks?
> > Thanks in advance for any help,
> > -pp
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