4 ms·

Could someone explain what a "stale chain" is and what the implication of this is?

• Nullabillity 6y ago
  Bitcoin requires a linear history (apart from the genesis block and the currently latest block, every block has exactly one parent and one child). If a block has multiple children, the one with the longest chain (of children) is selected in turn. The child (and its subchildren in turn) that is not selected is called "stale", and its transactions are effectively undone. This could be a used to try do a "double spend" (send X bitcoins to address A, rollback the transaction, send the same bitcoins to B instead). However, according to the OP's analysis that hasn't been attempted (yet), and the active chain is far enough ahead that it seems unlikely that the stale chain would ever catch up and overtake it.
  • maest 6y ago
    Length 2 seems quite short - I'd expect this to happen more often, surely.
    • siberianbear 6y ago
      Yeah, I had that same thought. A length of 4 or something seems unlikely to happen because a miner would almost have to be doing something nefarious to build on top of an already stale chain. A length of 2 could be some kind of concurrency/synchronization issue caused by one miner not having seen another miner's block in time to start mining on the "correct" chain.
    • lmpostor 6y ago
      Two reason why on BTC it doesn't. 1. Longer block times, so it is pretty rare that multiple miners are finding multiple valid consecutive blocks to compete on separate chains 2. It is against their incentives. By being apart of the losing chain, they have used thousands in hash power and missed out on possible tens of thousands that would come from the valid chain.