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Date: Tue, 5 Aug 2014 20:54:08 +0200
Message-ID: <CANEZrP0AXvF5EYvsdpYxGUi5yV9eD_8qUge80XCoaeyekfd67Q@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Jeff Garzik <jgarzik@bitpay.com>
Content-Type: multipart/alternative; boundary=089e011606026bacee04ffe661c4
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] deterministic transaction expiration
Precedence: list

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>
> The user experience of unconfirming transactions setting around in limbo
> is just horrible.  Bitcoin software by necessity has gotten better about
> attaching fees so this sort of behavior is uncommon, but that does not
> eliminate the problem.
>

Yes, indeed. I suspect there's a quick hack that could make this problem a
lot better though.

I think I brought up this idea before, but can't quite remember. Anyway I'm
willing to bet that if we analysed the data some more, we'd discover that
most "legitimate" i.e. non-DoS unconfirmed transactions that sit around for
ages are linked back to the block chain within two hops and not more. That
is people send a transaction that uses up their coin age, and then
immediately those coins are immediately respent again, but then those final
new coins are not spent.

On the other hand DoS attacks look like bouncing your coins around over and
over forever, i.e. more than two or three hops back to the chain.

So I wonder if making priority look back two or three transactions but not
more would help real users a lot, whilst not opening up any significant new
potential for DoS.

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #c=
cc solid;padding-left:1ex"><div dir=3D"ltr"><div><div><div>The user experie=
nce of unconfirming transactions setting around in limbo is just horrible.=
=C2=A0 Bitcoin software by necessity has gotten better about attaching fees=
 so this sort of behavior is uncommon, but that does not eliminate the prob=
lem.<br>
</div></div></div></div></blockquote><div><br></div><div>Yes, indeed. I sus=
pect there&#39;s a quick hack that could make this problem a lot better tho=
ugh.</div><div><br></div><div>I think I brought up this idea before, but ca=
n&#39;t quite remember. Anyway I&#39;m willing to bet that if we analysed t=
he data some more, we&#39;d discover that most &quot;legitimate&quot; i.e. =
non-DoS unconfirmed transactions that sit around for ages are linked back t=
o the block chain within two hops and not more. That is people send a trans=
action that uses up their coin age, and then immediately those coins are im=
mediately respent again, but then those final new coins are not spent.</div=
>
<div><br></div><div>On the other hand DoS attacks look like bouncing your c=
oins around over and over forever, i.e. more than two or three hops back to=
 the chain.</div><div><br></div><div>So I wonder if making priority look ba=
ck two or three transactions but not more would help real users a lot, whil=
st not opening up any significant new potential for DoS.=C2=A0</div>
</div></div></div>

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