[Spread-users] Spread for HA rpc services

John Robinson jr at vertica.com
Wed Aug 8 16:47:02 EDT 2007


Colin Meyer wrote:

> It seems easy enough for the non-lead processes to ignore requests. What
> happens when the current lead dies unexpectedly? The pool will receive
> the disconnect message, but how do all of the processes come to a
> consensus on which process is going to be the next lead?

Spread makes this pretty easy.  Each new membership list arrives at the 
same time, and is in the same order relative to regular messages (with 
high enough delivery class), at every process.  So simply designate the 
new process 0 as the leader from that point forward.  In-band membership 
change messages make this work nicely without need of a distributed 
voting algorithm.

/jr





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