[Spread-users] Intro

K. Richard Pixley rich at noir.com
Tue Nov 17 13:14:59 EST 2009

Hello.  The intro doc asked me to introduce myself so here I am.

I'm a spread newbie, but not entirely a newbie to virtual synchrony.  
Back in the 80's, I wrote a distributed wall street ticker plant, 
(Sequent Balance, Sequent Symmetry, Sun 3/50's, later Decstations), and 
later rewrote it in ISIS.  But that's been a few years ago now and the 
spread doc seems a bit lean in terms of background info by comparison to 
what I remember from ISIS.


Has anyone made any noise about updating the debian/ubuntu packages to 
spread version 4?  They seem to be a few years out of date, I'm in a 
position to volunteer the work, and I'll need packages anyway if I go 
through with my upcoming project using spread.

Also, using the python-spread package currently available on 
debian/ubuntu, how do I tell the ordinality/seniority of a group 
member?  Is that just something I need to track on my own and ship to 
joining processes as new state?

Here's a situation I'm unsure of.  I'm looking to create redundant, 
distributed state here.  A process is running and it sends a state 
change message at the same time as a second process joins.  Upon 
receiving the join message, the first process will send a state dump to 
the second process.  However, if the state dump message is formulated 
and sent prior to receiving the state change message, then isn't it 
conceivable that the messages will be received in the "join", "state 
change", "state dump" order effectively losing the "state change" 
message for the second process?

Is there a guarantee I'm overlooking here?  Or is there a standard way 
to deal with this situation?


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