3 ms·
> There is a separate consensus in a rare but common case of two consecutive ticks being associated with conflicting blocks. The conflict is resolved by what bl
by hudon 9y ago
> There is a separate consensus in a rare but common case of two consecutive ticks being associated with conflicting blocks. The conflict is resolved by what block will be associated with the next tick, rendering one of the disputed blocks “orphan”. How the chain will continue is a matter of chance
It being a "matter of chance" may be false and thus the thesis that this clock is "decentralized" should be questioned. There are situations where there will be conflicting blocks and no block gets orphaned unless a central authority commands it to be so. This was seen in the 2013 Bitcoin fork, when Pieter and Luke ordered the miners to move away from the majority chain (0.8) onto the minority chain (0.7) and this was also seen in 2016 when Vitalik ordered that a permanent chain divergence (ie. fork) happen. In both cases, the blockchain split and a central authority was necessary to resolve the conflict. It was not a matter of chance. The fact that this clock can have permanently divergent chains and that a central authority is required to say which chain should be chosen as the right one means that this clock is not decentralized.
- sethgecko 9y agoFascinating, I found this article by Vitalik that explains what happened. In v0.8 they swapped from BerkleyDB to LevelDB but due to a bug the two chains started diverting. https://bitcoinmagazine.com/articles/bitcoin-network-shaken-by-blockchain-fork-1363144448/ https://bitcoinmagazine.com/articles/bitcoin-network-shaken-...
- hudon 9y agoYup, we'll never know if the bug was intentional or not, and that's why the fix being centrally coordinated is scary. Maybe it was a legitimate mistake, but maybe one of the developers planned this and executed large double-spends on the 0.8 branch because he knew 0.7 would be ultimately chosen. The fact that nothing prevents this type of attack is worrisome. You can see how the developers behaved like a central authority in the IRC logs of the bitcoin-dev channel. More info here: https://freedom-to-tinker.com/2015/07/28/analyzing-the-2013-bitcoin-fork-centralized-decision-making-saved-the-day/ https://freedom-to-tinker.com/2015/07/28/analyzing-the-2013-...