On 6/19/06, Matthew Toseland <toad at amphibian.dyndns.org> wrote:
> On Sun, Jun 18, 2006 at 02:26:03PM -0500, David Sowder (Zothar) wrote:
> > Florent Daigni?re (NextGen$) wrote:
> > >* zothar at freenetproject.org <zothar at freenetproject.org> [2006-06-18
> > >19:02:38]:
> > >
> > >>Author: zothar
> > >>Date: 2006-06-18 19:02:33 +0000 (Sun, 18 Jun 2006)
> > >>New Revision: 9304
> > >>
> > >>Modified:
> > >>   trunk/freenet/src/freenet/node/RequestSender.java
> > >>Log:
> > >>Mitigate "backoff hell" a bit by not routing to a peer if it's the only
> > >>one not backed off and we have a few backed off peers.
> > >
> > >That's what we call alchemy, isn't it ? :)
> > >
> > >Well, I do see the point of not sending our requests when we have only
> > >one online peer (even if there is plausible deniability) but why the
> > >"backoff throwsold" ? to allow nodes with less than 4 peers to be usable
> > >?
> > >I'm not sure I agree to the concept, maybe I'm missing the point though,
> > >may you explain ? :)
> > >
> > When I got back to my node after being away from it for 24 hours
> > Saturday night, it was in what I call "backoff hell".  I've seen
> > "backoff hell" at least one other time.  It's when all of your connected
> > peers are backed off and every time one of them comes out of backoff, it
> > goes right back into back off very quickly.  I assume this is because my
> > node is eager to send that node anything it has, no matter how misrouted
> > it is.  I don't recall from last time, but I must admit that this time,
> > the reason was usually timeouts rather than overloads.  You're right,
> > the backoff threshold is so that nodes with fewer than 4 peers don't
> > have this restriction.
>
> Are you sure that it wasn't due to some external factor, like high CPU
> usage, or network saturation?
> >
> > I agree that this is alchemy, but I figure it'll give a node more of a
> > fighting chance of recovering from "backoff hell" and since that's the
> > only time it'd apply, the impact otherwise should be nil.  Perhaps some
> > of the SoC work this summer will make such alchemy unneeded.  However,
> > just because it's alchemy doesn't mean it can't be useful.
>
> Hmmm... I will have a look at it when I get around to reading the
> commit...
> --



> Matthew J Toseland - toad at amphibian.dyndns.org
> Freenet Project Official Codemonkey - http://freenetproject.org/
> ICTHUS - Nothing is impossible. Our Boss says so.
>
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>

This does seem to make "some" sense in that a 50/50 choice between two
routes should give better routing than no choice at all...  It might
be what's needed to prevent a complete routing collapse or a feedback
loop, assuming everything else is bug-free.

-- 
I may disagree with what you have to say, but I shall defend, to the
death, your right to say it. - Voltaire

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