[Spread-users] Broadcast UDP messages will flood network and decrease performance

[John Schultz]

On Fri, 1 Feb 2008, John Robinson wrote:

> Would it be better if the recovers always sent full messages?  Assuming holes 
> are rare the incremental cost over optimal would not be too great.

This would mean then that only daemons that have gotten the full message 
can act as recovery nodes.  However, this might not be a bad trade off to 
make.

On your assumption, I would say that holes are rare on a LAN, but not on a 
WAN.  On a LAN, most of your daemons are probably going to be in one or 
two segments and so you are going to be sending the full message to the 
segment usually regardless.  Unless you further complicate sending by 
using unicast to pick out the daemons that need the full message and 
broadcast the meta-message.

There are lots of different tradeoffs and strategies that you could use.

---
John Schultz
Spread Concepts
Phn: 443 838 2200

> Treading a little off the list, but John started it ;-)...
>
> John Schultz wrote:
>> A trickier problem occurs when the membership of the group changes around 
>> the time of a send. 
> ...
>> A similar problem is that
>> daemons trying to recover message A for daemon #1 may also have the 
>> incorrect view of him and will answer his requests with the wrong version. 
>> So, maybe once Daemon #1 incorrectly gets the meta version he will have to 
>> re-request the full version explicitly somehow.
>
>
> /jr
>
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