Again, a block with 0 transactions is accepted

[leijurv]

How about instead of rejecting the block when it doesn't have at least 50% of the unconfirmed transactions you know of, you just don't relay it? Then you don't need 51% of the network to follow this new rule. Also, this rule may vary from node to node. Some nodes might have a ton of unconfirmed transactions they know about, so they reject a certain block that contains just under 50% of them, but the other nodes don't know about as many of those transactions, so they accept the block. (This is rather rare, though. The amount of unconfirmed transactions that each node knows about should equalize as transactions propagate) Those nodes could then fork the blockchain. Having it accept but just not relay those problematic blocks would solve that problem.

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[leijurv]

I think DannyHamilton is right. If a non-empty block is mined right now, then the time distance from now until the next non-empty block is (which will include your transaction), on average, 10 minutes. If an empty block is found in between, then it's still 10 minutes.

If a miner has just mined a block which includes your transaction, and is about to broadcast it, but then it receives an empty block, it doesn't say "Oh dang. Someone found a block. Now I have to wait another ten minutes until I'l allowed to mine another block. Better shut off the ASICs until then so I don't waste electricity" No. It just keeps on mining and will mine a block with your transaction much sooner than that (on average, because it's already been mining for a while).

[aaaxn]

Of course miners that mine empty blocks delays transactions.
They might be not affecting average block time, but they affect average 'block with transactions' time and that matters.

Do we have at least one empty block every 2016 blocks (probably yes)? If yes then such miners delay transactions all the time.

[mezzomix]

It's simple: A miner is free to include any transaction he wants. I'm operating a few well connected nodes. I'm free to not relay blocks that do not contain at least a minimum amount of transactions until the next block is found. I patched my clients to prevent relaying those blocks to give miners an incentive to include transactions. I do not relay the last block in the chain when I have a certain amount of open transactions in my pool, the block is the last block and the block included a much lower number of transactions than my pool when I first saw it.

Maybe we should include this feature into the official client to give miners an incentive to include transactions?!

[solex]

How about instead of rejecting the block when it doesn't have at least 50% of the unconfirmed transactions you know of, you just don't relay it?

Can of worms there. You would have a solved block discarded which contains dozens of transactions which people have been waiting on for a confirmation? Also, a spammer could immediately cripple the network by generating loads of new transactions. A few weeks ago I saw over 12,000 unconfirmed on blockchain.info, most were not legitimate. Only 2400 (on average) fit into the current block limit.

[justusranvier]

tl;dr

How about if you don't like what some miners are doing with regards to block creation, then start mining yourself so that you can enforce your own policy for which transactions get included in a block?

[mezzomix]

Mining yourself is not an option. You have no chance against the pools. The only thing everybody can do and should do is to establish a relay policy for blocks. Each miner (pool) is free to include whatever he wants but each node operator is free as well to relay whatever he wants. Without a relay policy you hand over to much power to the pools. The miners get a lot of money for doing their work. Part of this work is to include transactions. If miners act against my interest and do not include transactions I will not relay their blocks.

[Shevek]

I'm becoming too old. I remember this exact discussion and proposed solutions when so called mystery miner gained significant percentage of the hash power and did not included any transactions besides the coinbase. The exact same discussion.

https://bitcointalk.org/index.php?topic=67634.20
There were more topics. Not sure if this is THE one.

Thanks for the tip. Not everbody here are "becoming" as old as you  and these appointments are useful.

[Shevek]

Not a big deal, really.

It depends on how often they become.

Nevertheless, I think this is a weakness of the protocol.

[Shevek]

BTW somebody figures out how to poll the apis of blockexplorer.com / blockchain.info to get the list of blocks with only the generation TX?

[leijurv]

How about instead of rejecting the block when it doesn't have at least 50% of the unconfirmed transactions you know of, you just don't relay it?

Can of worms there. You would have a solved block discarded which contains dozens of transactions which people have been waiting on for a confirmation? Also, a spammer could immediately cripple the network by generating loads of new transactions. A few weeks ago I saw over 12,000 unconfirmed on blockchain.info, most were not legitimate. Only 2400 (on average) fit into the current block limit.

Hmmm. I suppose so.

[cp1]

I think DannyHamilton is right. If a non-empty block is mined right now, then the time distance from now until the next non-empty block is (which will include your transaction), on average, 10 minutes. If an empty block is found in between, then it's still 10 minutes.

If a miner has just mined a block which includes your transaction, and is about to broadcast it, but then it receives an empty block, it doesn't say "Oh dang. Someone found a block. Now I have to wait another ten minutes until I'l allowed to mine another block. Better shut off the ASICs until then so I don't waste electricity" No. It just keeps on mining and will mine a block with your transaction much sooner than that (on average, because it's already been mining for a while).

The miners producing empty blocks increase the difficulty.  So they do have an affect.

[mmeijeri]

The miners producing empty blocks increase the difficulty.  So they do have an affect.

All miners increase difficulty. All miners add value. Miners who only produce empty blocks produce less value than others.

[Shevek]

Miners who only produce empty blocks produce less value than others.

Let's say, the value they produce to bitcoin is much lesser than the value bitcoin produces for them.

[DannyHamilton]

Miners who only produce empty blocks produce less value than others.

Let's say, the value they produce to bitcoin is much lesser than the value bitcoin produces for them.

Let's just agree to disagree on that point, but the end result is that it isn't going to change without overwhelming support, and I think you'll find it extremely difficult to get the overwhelming support that you need.  There are many like me who prefer to just leave it the way it is.

[bezzeb]

Interesting discussion, but a few points seem to have been missed.

1.  The blockchain grew from nothing and there were long periods when 0 transaction blocks were normal in the early days.  You need a system that can handle everything from zero to infinity, and the bitcoin protocol does this well (provided pruning and such get good solutions to handle long term growth).

2.  This was said already, but a brilliant incentive exists already to include transactions:  Greed.  Fees will keep transactions flowing.  This current (and temporary) period of time where 25BTC rewards are issued for empty blocks has created a brief window where transactions might not be included by a rogue miner, but I still don't see the threat.  Proof of work is still required, and if they want to give their fees to the next miner, then they're idiots - i'll take the fees gladly.    As network use continues to grow the fees will I think quickly get more valuable than the reward.  Parity is almost certainly only 2 or 4 years away, and as the reward diminishes the problem will fix itself..

2a.  There is a bizarre edge case I thought of ages ago whereby one might be able to do a zero-tx block as a way of sort of "mining without the rush" - to essentially take as long as you wanted to process a block and then trick it into the network to snag the reward, but as I understand it now, I don't think this would work as you need the prior fresh block included in your proof of work declaration.  And this info only exists after said block is created.  And if a loophole existed here - the network would simply not work as everyone would dream up blocks in their free time and then apply them later, so I've discarded this notion completely.

3. Also said already - as long as the zero transaction block has valid proof of work, it does serve to secure prior transactions deeper in the chain.  So we're still getting part of what we need. 

4.  The statistical method used to deliver proof of work almost ensures that once in a very rare while (would love it if a statistician did the maths for us , a miner would come up with an honest zero tx block - especially if they had some flakey connectivity.  I mean there was only 100 seconds between the prior block and the zero block, so there could be any number of ways this could happen without screaming foul.  And it's possible blocks could be solved within just a few seconds of each other - throw of the dice really.

This leaves me saying:  Meh.  We'll survive.

All the other ideas which have been thrown around to somehow stop zero blocks have horrible repercussions as far as I can tell.  So in the end I also must ask if a "fix" for such an edge case problem could even be worth it.

Now if we see it start to happen 15 times a day, then ignore everything i said 'cause we some hacker biatches we need to drop a boot on!!!!

[Blowfeld]

... I think this is a weakness of the protocol.

How does an empty block (~250 bytes) do you more harm than any other 250 byte, 25BTC transaction?  [All I can see is that it (slightly) increases the difficulty two weeks from today.  But if it included one or more transactions, it would still (slightly) increase the difficulty two weeks from today.]  Yes, it's a lost opportunity to include transactions, but is it really any worse than if the miner hadn't been mining at all?

If it ain't broke, don't fix it.

[Shevek]

... I think this is a weakness of the protocol.

How does an empty block (~250 bytes) do you more harm than any other 250 byte, 25BTC transaction? 

Because bitcoin IS about transactions. So, NO transactions, NO bitcoin. It is easy to understand.

[All I can see is that it (slightly) increases the difficulty two weeks from today.  But if it included one or more transactions, it would still (slightly) increase the difficulty two weeks from today.]  Yes, it's a lost opportunity to include transactions, but is it really any worse than if the miner hadn't been mining at all?

If it ain't broke, don't fix it.

I said, it is a weakness of the protocol, but it does not mean that it is fixable.

[mezzomix]

... I think this is a weakness of the protocol.

How does an empty block (~250 bytes) do you more harm than any other 250 byte, 25BTC transaction?

My point of view is that the miners keep the block chain running and acknowledge transactions. If I miner is not willing to do the second point it does not deserve the 25 BTC. My reaction was to change my bitcoin nodes to accept all blocks but I do not relay a block block if it is the last block, it includes only a fraction of the possible transactions and my local transaction pool sees much more transactions. If I see a block that better fit my rules I replace this last block by the new one.

If everybody includes this kind of change an "empty" block miner will have a small disadvantage.

[solex]

This is a temporary problem, so why risk breaking the protocol with a change?

Fees are increasing steadily, and the block reward halves every four years. Probably during the time the reward is 12.5 BTC the fees per block will be begin exceeding that amount. So any miner producing empty blocks will be throwing away 50% of his potential revenue. Because difficulty will probably be 500+ million it will be uneconomic to mine empty blocks.