Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
Hi all, I've also been spending a few months coding upon the change's Pieter has been making with the headersfirst8 pull request. My code updates are also ready to test, and are available on github at https://github.com/rebroad/bitcoin/ and the branch is sipa-headersfirst8-patches. I've made a number of improvement. Namely that it tracks the block as it downloads and won't disconnect if the block is downloading at a reasonable speed. The current stall logic of Pieter's is broken in that it will continue to disconnect a peer that is providing a block - particularly the next block needed to advance the current tip. I've raised this issue, but so far haven't been able to communicate the problem in a way that's been understood. I've also added logic to avoid the node stalling due to many blocks being added to the ActiveTip (which would cause timeouts both from our node, and nodes we are connected to). It will also log and determine bandwidth per node, and the next changes I will be adding will be to make it prefer to download from the faster nodes (coming shortly). I have also added code ready to adapt the window size for the download. Currently the start setting for blocks in flight is 3 per node, but for early on on the block chain this will be too small, so once it realises this after a few downloads and determines the average block size and speed, it will automatically adjust the number of blocks to request per node and revise this each minute. Please do take a look at my code, and feel free to test it. It also improves some of the debug.log output to make it easier to read and provide useful information about concurrent downloads, etc. Edmund On Sun, Oct 12, 2014 at 7:34 AM, Pieter Wuille pieter.wui...@gmail.com wrote: Hi all, I believe that a large change that I've been working on for Bitcoin Core is ready for review and testing: headers-first synchronization. In short, it changes the way the best chain is discovered, downloaded and verified, with several advantages: * Parallel block downloading (much faster sync on typical network connections). * No more stalled downloads. * Much more robust against unresponsive or slow peers. * Removes a class of DoS attacks related to peers feeding you low-difficulty valid large blocks on a side branch. * Reduces the need for checkpoints in the code. * No orphan blocks stored in memory anymore (reducing memory usage during sync). * A major step step towards an SPV mode using the reference codebase. Historically, this mode of operation has been known for years (Greg Maxwell wrote up a description of a very similar method in https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync in early 2012, but it was known before that), but it took a long time to refactor these code enough to support it. Technically, it works by replacing the single-peer blocks download by a single-peer headers download (which typically takes seconds/minutes) and verification, and simultaneously fetching blocks along the best known headers chain from all peers that are known to have the relevant blocks. Downloading is constrained to a moving window to avoid unbounded unordering of blocks on disk (which would interfere with pruning later). At the protocol level, it increases the minimally supported version for peers to 31800 (corresponding to bitcoin v3.18, released in december 2010), as earlier versions did not support the getheaders P2P message. So, the code is available as a github pull request (https://github.com/bitcoin/bitcoin/pull/4468), or packaged on http://bitcoin.sipa.be/builds/headersfirst, where you can also find binaries to test with. Known issues: * At the very start of the sync, especially before all headers are processed, downloading is very slow due to a limited number of blocks that are requested per peer simultaneously. The policies around this will need some experimentation can certainly be improved. * Blocks will be stored on disk out of order (in the order they are received, really), which makes it incompatible with some tools or other programs. Reindexing using earlier versions will also not work anymore as a result of this. * The block index database will now hold headers for which no block is stored on disk, which earlier versions won't support. If you are fully synced, it may still be possible to go back to an earlier version. Unknown issues: * Who knows, maybe it will replace your familiy pictures with Nyan Cat? Use at your own risk. TL;DR: Review/test https://github.com/bitcoin/bitcoin/pull/4468 or http://bitcoin.sipa.be/builds/headersfirst. -- Pieter -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
When forgoing bootstrapping due to disk space constraints, you, and the network, are likely better off -reindex-ing from current blk000??.dat files. Which brings up an interesting point: The improvements related to the headers first approach are likely to increase, how ever marginally, the percentage of block exchange-related traffic, as it is less painful now to be catching up. It'd be interesting to see the statistics, not from a single node perspective, but from the viewpoint of an Internet backbone provider, say through the cables coming ashore in Cornwall. For the incurred bandwidth expense would invariably trickle down to transaction fees in an equilibrium model. There is an opportunity somewhere in this. On Sun, Oct 12, 2014 at 7:13 PM, Jameson Lopp jameson.l...@gmail.com wrote: Great work, Pieter. I've been spooling up several nodes per week lately and can testify that stalled downloads during initial syncing are a pain. I usually forgo bootstrapping on VPSes because I don't want to have to adjust the disk space allocation. With headers-first I'm saturating my home cable connection with download rates of 4 MB/s until block 295,000 at which point CPU becomes the bottleneck and it settles down in the 1 MB/s range. It took 6 minutes for my node to sync to block height 100,000 22 minutes to reach height 200,000 62 minutes to reach height 250,000 125 minutes to reach height 295,000 144 minutes to reach height 300,000 248 minutes to reach height 325,000 - Jameson On 10/11/2014 07:34 PM, Pieter Wuille wrote: Hi all, I believe that a large change that I've been working on for Bitcoin Core is ready for review and testing: headers-first synchronization. In short, it changes the way the best chain is discovered, downloaded and verified, with several advantages: * Parallel block downloading (much faster sync on typical network connections). * No more stalled downloads. * Much more robust against unresponsive or slow peers. * Removes a class of DoS attacks related to peers feeding you low-difficulty valid large blocks on a side branch. * Reduces the need for checkpoints in the code. * No orphan blocks stored in memory anymore (reducing memory usage during sync). * A major step step towards an SPV mode using the reference codebase. Historically, this mode of operation has been known for years (Greg Maxwell wrote up a description of a very similar method in https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync in early 2012, but it was known before that), but it took a long time to refactor these code enough to support it. Technically, it works by replacing the single-peer blocks download by a single-peer headers download (which typically takes seconds/minutes) and verification, and simultaneously fetching blocks along the best known headers chain from all peers that are known to have the relevant blocks. Downloading is constrained to a moving window to avoid unbounded unordering of blocks on disk (which would interfere with pruning later). At the protocol level, it increases the minimally supported version for peers to 31800 (corresponding to bitcoin v3.18, released in december 2010), as earlier versions did not support the getheaders P2P message. So, the code is available as a github pull request (https://github.com/bitcoin/bitcoin/pull/4468), or packaged on http://bitcoin.sipa.be/builds/headersfirst, where you can also find binaries to test with. Known issues: * At the very start of the sync, especially before all headers are processed, downloading is very slow due to a limited number of blocks that are requested per peer simultaneously. The policies around this will need some experimentation can certainly be improved. * Blocks will be stored on disk out of order (in the order they are received, really), which makes it incompatible with some tools or other programs. Reindexing using earlier versions will also not work anymore as a result of this. * The block index database will now hold headers for which no block is stored on disk, which earlier versions won't support. If you are fully synced, it may still be possible to go back to an earlier version. Unknown issues: * Who knows, maybe it will replace your familiy pictures with Nyan Cat? Use at your own risk. TL;DR: Review/test https://github.com/bitcoin/bitcoin/pull/4468 or http://bitcoin.sipa.be/builds/headersfirst. -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
On Sat, Oct 11, 2014 at 11:34 PM, Pieter Wuille pieter.wui...@gmail.com wrote: * Parallel block downloading (much faster sync on typical network connections). Much faster is an understatement. Benchmarking here shows one hour five minutes syncing to 295000. Old code isn't even at 25 after 7 hours. (I'm using 295k as the target here because after that point ecdsa dominates, and then your 6+x faster libsecp256k1 makes more of a difference) -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
On 12.10.2014 01:34, Pieter Wuille wrote: * No orphan blocks stored in memory anymore (reducing memory usage during sync). Will this slow down reorgs after a fork, compared to today? Regards, Geir H. Hansen, Bitminter -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
On Sunday, October 12, 2014 8:41:29 AM Geir Harald Hansen wrote: On 12.10.2014 01:34, Pieter Wuille wrote: * No orphan blocks stored in memory anymore (reducing memory usage during sync). Will this slow down reorgs after a fork, compared to today? It shouldn't... he's talking about actual orphan blocks (ones without a known previous/parent block), not stale blocks. Luke -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
On Sun, Oct 12, 2014 at 10:41 AM, Geir Harald Hansen opera...@bitminter.com wrote: On 12.10.2014 01:34, Pieter Wuille wrote: * No orphan blocks stored in memory anymore (reducing memory usage during sync). Will this slow down reorgs after a fork, compared to today? Why would you think so? Orphan blocks are blocks whose parent is not known. In the case of a reorganization the client 'jumps' to a new best chain, for this to happen the original tip and the new best tip and all their parents must be already known. Wladimir -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
[Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
Hi all, I believe that a large change that I've been working on for Bitcoin Core is ready for review and testing: headers-first synchronization. In short, it changes the way the best chain is discovered, downloaded and verified, with several advantages: * Parallel block downloading (much faster sync on typical network connections). * No more stalled downloads. * Much more robust against unresponsive or slow peers. * Removes a class of DoS attacks related to peers feeding you low-difficulty valid large blocks on a side branch. * Reduces the need for checkpoints in the code. * No orphan blocks stored in memory anymore (reducing memory usage during sync). * A major step step towards an SPV mode using the reference codebase. Historically, this mode of operation has been known for years (Greg Maxwell wrote up a description of a very similar method in https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync in early 2012, but it was known before that), but it took a long time to refactor these code enough to support it. Technically, it works by replacing the single-peer blocks download by a single-peer headers download (which typically takes seconds/minutes) and verification, and simultaneously fetching blocks along the best known headers chain from all peers that are known to have the relevant blocks. Downloading is constrained to a moving window to avoid unbounded unordering of blocks on disk (which would interfere with pruning later). At the protocol level, it increases the minimally supported version for peers to 31800 (corresponding to bitcoin v3.18, released in december 2010), as earlier versions did not support the getheaders P2P message. So, the code is available as a github pull request (https://github.com/bitcoin/bitcoin/pull/4468), or packaged on http://bitcoin.sipa.be/builds/headersfirst, where you can also find binaries to test with. Known issues: * At the very start of the sync, especially before all headers are processed, downloading is very slow due to a limited number of blocks that are requested per peer simultaneously. The policies around this will need some experimentation can certainly be improved. * Blocks will be stored on disk out of order (in the order they are received, really), which makes it incompatible with some tools or other programs. Reindexing using earlier versions will also not work anymore as a result of this. * The block index database will now hold headers for which no block is stored on disk, which earlier versions won't support. If you are fully synced, it may still be possible to go back to an earlier version. Unknown issues: * Who knows, maybe it will replace your familiy pictures with Nyan Cat? Use at your own risk. TL;DR: Review/test https://github.com/bitcoin/bitcoin/pull/4468 or http://bitcoin.sipa.be/builds/headersfirst. -- Pieter -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
Re: [Bitcoin-development] Request for review/testing: headers-first synchronization in Bitcoin Core
This is great Pieter. I was able to sync the entire blockchain from scratch in a little over 4 hours on a laptop over cable modem. :) No issues to report. Even my family photos are intact! This makes it practical to run a full node, part time on a laptop again. Aaron Voisine breadwallet.com On Sat, Oct 11, 2014 at 4:34 PM, Pieter Wuille pieter.wui...@gmail.com wrote: Hi all, I believe that a large change that I've been working on for Bitcoin Core is ready for review and testing: headers-first synchronization. In short, it changes the way the best chain is discovered, downloaded and verified, with several advantages: * Parallel block downloading (much faster sync on typical network connections). * No more stalled downloads. * Much more robust against unresponsive or slow peers. * Removes a class of DoS attacks related to peers feeding you low-difficulty valid large blocks on a side branch. * Reduces the need for checkpoints in the code. * No orphan blocks stored in memory anymore (reducing memory usage during sync). * A major step step towards an SPV mode using the reference codebase. Historically, this mode of operation has been known for years (Greg Maxwell wrote up a description of a very similar method in https://en.bitcoin.it/wiki/User:Gmaxwell/Reverse_header-fetching_sync in early 2012, but it was known before that), but it took a long time to refactor these code enough to support it. Technically, it works by replacing the single-peer blocks download by a single-peer headers download (which typically takes seconds/minutes) and verification, and simultaneously fetching blocks along the best known headers chain from all peers that are known to have the relevant blocks. Downloading is constrained to a moving window to avoid unbounded unordering of blocks on disk (which would interfere with pruning later). At the protocol level, it increases the minimally supported version for peers to 31800 (corresponding to bitcoin v3.18, released in december 2010), as earlier versions did not support the getheaders P2P message. So, the code is available as a github pull request (https://github.com/bitcoin/bitcoin/pull/4468), or packaged on http://bitcoin.sipa.be/builds/headersfirst, where you can also find binaries to test with. Known issues: * At the very start of the sync, especially before all headers are processed, downloading is very slow due to a limited number of blocks that are requested per peer simultaneously. The policies around this will need some experimentation can certainly be improved. * Blocks will be stored on disk out of order (in the order they are received, really), which makes it incompatible with some tools or other programs. Reindexing using earlier versions will also not work anymore as a result of this. * The block index database will now hold headers for which no block is stored on disk, which earlier versions won't support. If you are fully synced, it may still be possible to go back to an earlier version. Unknown issues: * Who knows, maybe it will replace your familiy pictures with Nyan Cat? Use at your own risk. TL;DR: Review/test https://github.com/bitcoin/bitcoin/pull/4468 or http://bitcoin.sipa.be/builds/headersfirst. -- Pieter -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development -- Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://p.sf.net/sfu/Zoho ___ Bitcoin-development mailing list Bitcoin-development@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-development
