Subject: Re: [Bitcoin-development] Warning: many 0.7 nodes break on large number of tx/block; fork risk

From: Pieter Wuille <[email-masked]>
Date: Tue, 12 Mar 2013 02:01:35 +0100

Hello again,

block 000000000000015c50b165fcdd33556f8b44800c5298943ac70b112df480c023
(height=225430) seems indeed to have cause pre-0.8 and 0.8 nodes to fork
(at least mostly). Both chains are being mined on - the 0.8 one growing
faster.

After some emergency discussion on #bitcoin-dev, it seems best to try to
get the majority mining power back on the "old" chain, that is, the one
which 0.7 accepts
(with 00000000000001c108384350f74090433e7fcf79a606b8e797f065b130575932 at
height 225430). That is the only chain every client out there will accept.
BTC Guild is switching to 0.7, so majority should abandon the 0.8 chain
soon.

Short advice: if you're a miner, please revert to 0.7 until we at least
understand exactly what causes this. If you're a merchant, and are on 0.8,
stop processing transactions until both sides have switched to the same
chain again. We'll see how to proceed afterwards.

-- 
Pieter

On Tue, Mar 12, 2013 at 1:18 AM, Pieter Wuille <[email-masked]>wrote:

> Hello everyone,
>
> Í've just seen many reports of 0.7 nodes getting stuck around block
> 225430, due to running out of lock entries in the BDB database. 0.8 nodes
> do not seem to have a problem.
>
> In any case, if you do not have this block:
>
>   2013-03-12 00:00:10 SetBestChain: new
> best=000000000000015aab28064a4c521d6a5325ff6e251e8ca2edfdfe6cb5bf832c
>  height=225439  work=853779625563004076992  tx=14269257  date=2013-03-11
> 23:49:08
>
> you're likely stuck. Check debug.log and db.log (look for 'Lock table is
> out of available lock entries').
>
> If this is a widespread problem, it is an emergency. We risk having
> (several) forked chains with smaller blocks, which are accepted by 0.7
> nodes. Can people contact pool operators to see which fork they are on?
> Blockexplorer and blockchain.info seem to be stuck as well.
>
> Immediate solution is upgrading to 0.8, or manually setting the number of
> lock objects higher in your database. I'll follow up with more concrete
> instructions.
>
> If you're unsure, please stop processing transactions.
>
> --
> Pieter
>