This thread can be hard to follow if you're not following it all the time!  

The question was in reference to a debate I was having with Odalv about these "order of magnitude" estimates shown in this table.  I was suggesting that, under the conditions considered in the table, it is cheaper for miners to write the spam to the Blockchain and more costly for the spammer, than continually rejecting it:




Sorry, yes I know you explained that.  The point I'm trying to make is that if CreateNewBlock is super-linear in mempool size, then it would not be surprising to see more empty blocks (what Cypher was calling "defensive blocks") when mempool swells (the miners are mining on an empty block for longer while waiting for CreateNewBlock to finish).  This was Cypher's point from the very beginning that many people, including myself, were suggesting was probably not the case!  

Furthermore, how can f2pool/antpool mine a non-empty block without calling createnewblock?

I just want to highlight the comments here from bitcoin-dev today, which seem to indicate that these spamming attacks would have been 5.5x more expensive if a dust threshold software change had not been made. Perhaps there are deeper insights someone else has on this...?

i don't think it really matters, does it?

since most of the mined blocks are filled with real demand trying to get into blocks with or without spamming, the only difference being that with spamming the real demand has to pay significantly higher fees to get in, the cost to fill up the rest of the block with spam is minimal as is the minimal cost to bloat the mempool to extraordinary levels (94K 0confs as i write).  i say minimal cost for the mempool b/c most of it gets turned over after 24h deletion allowing that spam to be recycled w/o having to pay.

When miner's mempool exceeds block size by some backlog factor, they need to send out a message to the peers they are connected to saying "don't propagate transactions to me with smaller than X fee per kilobyte until further notice". This will mitigate the impact that spam-that-can-never-be-added-to-a-block can have on the network, but it won't entirely eliminate it, because as the mempool backlog reduces, the miner will need to back off the notice to some unknown lower fee threshold. The miner could guess but it will never be 100% accurate. So spam will get verified and rejected. But perhaps those estimates can be close enough that the losses the spammers takes in fees for transactions it sends that do get into a block will be greater than the gains it values from effective spamming (what ever those gains are  ). Appears to me the issue can be fixed.

Afaik, the reason incoming transactions are verified before it is known whether they will be in a new block, is because it is considered spam to propagate (send out again to another peer) invalid transactions that would be rejected and never appear in a block.

Don't worry.  According to Mike Hearn Bitcoin can survive just fine with 4 or 6 (forgot which) copies of the blockchain worldwide.

It provided evidence that the network can handle the increased load, and it confirmed that people do get frustrated by the confirmation delays. 

Unfortunately, the majority in the blocks I checked earlier today have been the DOS attack-- e.g. transactions tracable from outputs of this transaction https://blockchain.info/tx/3bad15167c60de483cd32cb990d1e46f0a0d8ab380e3fc1cace01afc9c1bb5af  and a few others. ... though the attack style has been shifting to evade filtering by miners.

The change mentioned in the chat above is https://github.com/bitcoin/bitcoin/pull/3305 (you might find the comments there interesting), it's one of Mikes couple contributions to Bitcoin Core.

Jeff Garzik has just posted 2 pull requests for bitcoin core on github:

https://github.com/bitcoin/bitcoin/pull/6405
Remove TX priority and free transaction area from mempool, block creator.

https://github.com/bitcoin/bitcoin/pull/6402
Floating network relay fee increase, if memory pool grows too large.

the latter will introduce, if merged, "a relay fee that adjusts to floods
which cause the memory pool to grow too large".

It seems that core devs start becoming aware of the lack of
of economic incentives for services provided by full nodes.

Nah, there were also 364354, 364383, 364393 and 364398

In the short run, miners will keep putting up with spam transactions because most of their revenue (great majority) is coming from the BTC block reward. As rewards become less and less and transaction volume (spam or legitimate) continues to increase the balance will gradually start to change.

Eventually miners will start to ignore transactions without some minimum transaction fee (which will change over time based on block reward/transaction fee balance).

This is a self correcting problem which miners will correct on their own (by only verifying transactions with some minimum fee)

We all expected this from the beginning. The blockchain will eventually be supported by transactions fees as block reward keeps dropping. The only thing that has changed is that miners may respond sooner because of all these spam transactions. Spam will stop once the miners raise the minimum fee enough (or spam transactions will continue but never be confirmed)