[Bitcoin-development] Punishing empty blocks?
luke at dashjr.org
Thu May 24 20:31:38 UTC 2012
On Thursday, May 24, 2012 4:33:12 PM Jeff Garzik wrote:
> There appears to be some non-trivial mining power devoted to mining
> empty blocks. Even with satoshi's key observation -- hash a fixed
> 80-byte header, not the entire block -- some miners still find it
> easier to mine empty blocks, rather than watch the network for new
> Therefore I was wondering what people thought about a client
> implementation change:
> - Do not store or relay empty blocks, if time since last block < X
> (where X = 60 minutes, perhaps)
> or even stronger,
> - Ensure latest block includes at least X percent of mempool
> unconfirmed TXs
These are problematic for legitimate miners:
1) The freedom to reject transactions based on fees or spam filters, is
severely restricted. As mentioned in other replies, this is an important point
of Bitcoin's design.
1b) This punishes miners with superior transaction spam filtering. As with all
spam filtering, it is often an "arms race" and therefore the filter rules must
be kept private by the miners, and therefore cannot be disclosed for the
validating clients to take into consideration.
2) For a few seconds after a new block is received, the new transaction merkle
root(s) are not finished calculating. During this time, most miners are
working on "blank" blocks with the new previousblockhash but no transactions.
If those blocks are ignored, miners are forced to shutdown mining during this
3) As you mentioned, illegitimate miners can easily workaround these
restrictions (even the second one, by flooding the network with their own
transactions). This puts the legitimate miners at a disadvantage in their own
search for valid blocks, unless they also come up with counter-measures
The argument that these are not rule changes is flawed:
1) As of right now, 99% of the network runs a single client. Anything this
client rejects does de facto become a rule change.
2) Even if there were a diverse ecosystem of clients in place, discouragement
rules that potentially affect legitimate miners significantly mess with the
odds of finding a block.
3) If legitimate miners do not adopt counter-rules to bypass these new
restrictions, the illegitimate miners are left with an even larger percentage
of blocks found.
To summarize, I believe such a change as proposed would be very harmful to
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