Re: [Bitcoin-development] Economics of information propagation
I haven't done the math on this, so it may be a terrible idea. :) I've been wondering if block propagation times could also be improved by allowing peers to request the list of transaction hashes that make up a block, and then making a follow-up request to only download any transactions not currently known. I'm not sure what percentage of transactions a node will usually already have when it receives a new block, but if it's high I figure this could be beneficial. Date: Mon, 21 Apr 2014 09:00:09 -0700 From: m...@monetize.io To: p...@petertodd.org; jonathan.le...@sant.ox.ac.uk CC: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Economics of information propagation That wasn't what I was saying. Right now the primacy of a block is determined by the time at which the `block` message is received, which is delays due to both the time it takes to transmit the block data and the time it takes to validate. Headers-first, on the other hand, has the option of basing primacy on the time the block header is received, which is O(1) time to transmit and to SPV-validate. Mining on that block doesn't actually commence until the full block is received and validated. To see how this works, take an example: two blocks with a common parent are found relatively close to each other, block A and block B. A is found first but is a large block with the maximum block size and many slow scripts. B is found a few seconds later and is an empty block. In the current regime it is entirely possible that block B, the later but smaller block, would get received and processed first by more mining peers than the larger block A, exactly as described in Jonathan Levin's email. With headers-first, however, the cost of propagation of the block header is the same and we should expect block A to win out over block B nearly every time. Miners will continue working on the old, known valid parent block until the contents of block A are received and processed. So the smaller block B is still found, and since it's data moves across the network faster, miners even briefly mine on block B. But as soon as they receive and process the contents of block A, they switch to that. The earlier, larger block A will only become stale if *two* blocks are found in the extra time it takes for block A to propagate the network. That is a substantially different risk, and probably a negligible concern to most miners. On 04/20/2014 09:06 PM, Peter Todd wrote: That is mistaken: you can't mine on top of just a block header, leaving small miners disadvantaged as they are earning no profit while they wait for the information to validate the block and update their UTXO sets. This results in the same problem as before, as the large pools who mine most blocks can validate either instantly - the self-mine case - or more quickly than the smaller miners. Of course, in reality smaller miners can just mine on top of block headers and include no transactions and do no validation, but that is extremely harmful to the security of Bitcoin. -- Start Your Social Network Today - Download eXo Platform Build your Enterprise Intranet with eXo Platform Software Java Based Open Source Intranet - Social, Extensible, Cloud Ready Get Started Now And Turn Your Intranet Into A Collaboration Platform http://p.sf.net/sfu/ExoPlatform ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Start Your Social Network Today - Download eXo Platform Build your Enterprise Intranet with eXo Platform Software Java Based Open Source Intranet - Social, Extensible, Cloud Ready Get Started Now And Turn Your Intranet Into A Collaboration Platform http://p.sf.net/sfu/ExoPlatform___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Why are we bleeding nodes?
I hope I'm not thread-jacking here, apologies if so, but that's the approach I've taken with the node I'm working on. Headers can be downloaded and stored in any order, it'll make sense of what the winning chain is. Blocks don't need to be downloaded in any particular order and they don't need to be saved to disk, the UTXO is fully self-contained. That way the concern of storing blocks for seeding (or not) is wholly separated from syncing the UTXO. This allows me to do the initial blockchain sync in ~6 hours when I use my SSD. I only need enough disk space to store the UTXO, and then whatever amount of block data the user would want to store for the health of the network. This project is a bitcoin learning exercise for me, so I can only hope I don't have any critical design flaws in there. :) From: ta...@bitsofproof.com Date: Mon, 7 Apr 2014 21:20:31 +0200 To: gmaxw...@gmail.com CC: bitcoin-development@lists.sourceforge.net Subject: Re: [Bitcoin-development] Why are we bleeding nodes? Once headers are loaded first there is no reason for sequential loading. Validation has to be sequantial, but that step can be deferred until the blocks before a point are loaded and continous. Tamas Blummerhttp://bitsofproof.com On 07.04.2014, at 21:03, Gregory Maxwell gmaxw...@gmail.com wrote:On Mon, Apr 7, 2014 at 12:00 PM, Tamas Blummer ta...@bitsofproof.com wrote: therefore I guess it is more handy to return some bitmap of pruned/full blocks than ranges. A bitmap also means high overhead and— if it's used to advertise non-contiguous blocks— poor locality, since blocks are fetched sequentially. -- Put Bad Developers to Shame Dominate Development with Jenkins Continuous Integration Continuously Automate Build, Test Deployment Start a new project now. Try Jenkins in the cloud. http://p.sf.net/sfu/13600_Cloudbees ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Put Bad Developers to Shame Dominate Development with Jenkins Continuous Integration Continuously Automate Build, Test Deployment Start a new project now. Try Jenkins in the cloud. http://p.sf.net/sfu/13600_Cloudbees___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Missing fRelayTxes in version message
I’m also running into this exact same issue with my parser, now I understand
why the relay field behavior I was seeing doesn’tmatch the wiki.
So to parse a version message, you can’t rely on the protocol version? You have
to know how long the payload is, and then parse the message accordingly? I
agree with Turkey Breast, this seems a bit sloppy to me.
Paul
P.S. I’ve never used a dev mailing list before and I want to get involved with
the Bitcoin dev community, so let me know if I’m horribly violating any mailing
list etiquette.
From: Mike Hearn
Sent: Wednesday, June 19, 2013 7:43 AM
To: Turkey Breast
Cc: bitcoin-development@lists.sourceforge.net
Bitcoin-Qt on master does send it now although it doesn't affect anything, but
as old pre-filtering versions will continue to exist, you'll always have to be
able to deserialize version messages without it.
Bitcoin version messages have always had variable length, look at how the code
is written in main.cpp. If you didn't experience issues until now all it means
is that no sufficiently old nodes were talking to yours.
The standard does not say it should appear. Read it again - BIP 37 says about
the new version message field:
If false then broadcast transactions will not be announced until a
filter{load,add,clear} command is received. If missing or true, no change in
protocol behaviour occurs.
On Wed, Jun 19, 2013 at 12:33 PM, Turkey Breast turkeybre...@yahoo.com wrote:
It's a problem if you work with iterators to deserialize the byte stream. Even
failing that, it's just sloppy programming. What happens in the future when new
fields are added to the version message? It's not a big deal to say that this
protocol version has X number of fields, that (higher) protocol version message
has X + N number of fields. Deterministic number of fields per protocol version
is sensical and how Bitcoin has been for a long time.
And yes, it was a problem for me that caused a lot of confusion why this byte
didn't exist in many version messages despite the standard saying it should and
the code in bitcoind indicating it should. Nowhere was this written. It doesn't
help other implementations to have an unclear behaviour that depends on some
magic from one implementation.
From: Mike Hearn m...@plan99.net
To: Turkey Breast turkeybre...@yahoo.com
Cc: bitcoin-development@lists.sourceforge.net
bitcoin-development@lists.sourceforge.net
Sent: Wednesday, June 19, 2013 11:39 AM
Subject: Re: [Bitcoin-development] Missing fRelayTxes in version message
It has to be optional because old clients don't send it, obviously.
Why is this even an issue? There's no problem with variable length messages in
any codebase that I'm aware of. Is this solving some actual problem?
On Wed, Jun 19, 2013 at 12:30 AM, Turkey Breast turkeybre...@yahoo.com wrote:
That's me. I never said to make all messages fixed length. I said to make a
fixed number of fields per protocol. So given a protocol version number, you
know the number of fields in a message. This is not only easier for parsing
messages, but just good practice. I don't see why a 1 byte flag needs to be
optional anyway.
From: Mike Hearn m...@plan99.net
To: Turkey Breast turkeybre...@yahoo.com
Cc: Bitcoin Dev bitcoin-development@lists.sourceforge.net
Sent: Tuesday, June 18, 2013 9:48 PM
Subject: Re: [Bitcoin-development] Missing fRelayTxes in version message
It's not a bug (although there was recently a change to make bitcoind/qt always
send this field anyway).
I don't know where Amir is going with BIP 60. Version messages have always been
variable length. There's nothing inherent in the Bitcoin protocol that says all
messages are fixed length, indeed, tx messages are allowed to have arbitrary
data appended after them that gets relayed.
On Tue, Jun 18, 2013 at 7:45 PM, Turkey Breast turkeybre...@yahoo.com wrote:
See this BIP. I'm not sure if this is a bug or what, but it would be good if
messages always had a fixed number of fields per protocol version.
https://en.bitcoin.it/wiki/BIP_0060#Code_Updates
This BIP details everything that needs to be done and proposes a protocol
upgrade.
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