Merge #561: Meetings: add 2018-06-14

2bc46d2 Meetings: add 2018-06-14 (David A. Harding)

Pull request description:

  Preview: http://dg1.dtrt.org/en/meetings/2018/06/14/

Tree-SHA512: 271abde4ba5a4800b045e2e66f236eb8e86a327b365fa2537fbf9031781f4dbc8665c659fa610b77f6e0c1dd01cd5dbc34af57c9d15ea181f4d2bfcb8f5fb43d

Author: harding

_posts/en/meetings/2018-06-14-meeting.md

@@ -0,0 +1,171 @@
+---
+title: IRC meeting summary for 2018-06-14
+lang: en
+permalink: /en/meetings/2018/06/14/
+name: 2016-06-14-meeting
+layout: page
+type: meetings
+version: 1
+---
+{% include _toc.html %}
+{% include _references.md %}
+
+- View this week's log on [BotBot.me][bbm log] or [MeetBot][mb log]
+- [Meeting minutes by MeetBot][mb minutes]
+
+---
+
+Topics discussed during this weekly meeting included what pull requests
+members of the project would like reviewers to focus on during the
+upcoming week, whether Bitcoin Core should optimize selecting which
+inputs to spend based on generating transactions that don't have change
+(better for privacy and fees) or transactions that only spend
+well-confirmed inputs (less likely to result in payment failures), and a
+few mini-topics mostly focused on optimizing SHA256d functions for
+various computer processor architectures.
+
+## High priority for review
+
+**Background:** each meeting, Bitcoin Core developers discuss which Pull
+Requests (PRs) the meeting participants think most need review in the
+upcoming week.  Some of these PRs are related to code that contributors
+especially want to see in the next release; others are PRs that are
+blocking further work or which require significant maintenance (rebasing)
+to keep in a pending state.  Any capable reviewers are encouraged to
+visit the project's list of [current high-priority
+PRs][].
+
+**Discussion ([log][log hipri]):** the following pending PRs were
+mentioned this week:
+
+- **[#12136][]:** Implement [BIP174][] Partially Signed Bitcoin Transactions
+  serialization and RPCs.  Removed from the list at the request of its
+  author, Andrew Chow, who said "It depends on [#13425][]."
+
+- **[#13425][]:** Moving final scriptSig construction from
+  CombineSignatures to ProduceSignatures.  Pieter Wuille commented,
+  "#13425 is pretty much all of the [Partially-Signed Bitcoin
+  Transactions] internal changes that are needed, excluding
+  serialization and RPCs."
+
+- **[#13111][]:** Add unloadwallet RPC.  Meeting comments indicated this
+  was close to being merged, after a final issue is addressed.
+
+- **[#13160][]:** Unlock spent outputs.  Suggested for the high-priority
+  list, but refused because its author already had an entry on the list.
+  Nevertheless, Wladimir van der Laan suggested it should receive more
+  attention.
+
+- **[#13439][]:** RPC: Avoid "duplicate" return value for invalid
+  submitblock.
+
+## SRD [Single Random Draw] fallback coin selection
+
+**Background:** several developers have been working on improving
+Bitcoin Core's coin selection---how it chooses which bitcoins (inputs)
+to spend---to simultaneously improve privacy, reduce transaction size,
+and reduce fees.  The current selection protocol starts with a
+Branch-and-Bound (BnB) algorithm that tries to find a match between the
+inputs available and the amount being sent.  If that doesn't work, a
+fallback algorithm is needed.  A Single-Random Draw (SRD) algorithm
+randomly adds additional inputs to a partial transaction until the sum
+of the inputs is equal to or greater than the amount being spent
+(including fees).
+
+**Discussion ([log][log srd]):** Andrew Chow requested and introduced
+the topic, "I think we should discuss [Gregory Sanders's] point
+[here][instagibbs comment]."  The cited comment says, "This new logic
+means that non-BnB will be tried more often.  Instead of trying all
+variants of BnB (6 confirms, 1 confirm, small chain, etc...), we seem to
+be [switching to] trying 6 confirms for BnB, then 6 confirms for
+non-BnB. [...]  I prefer the [previous] behavior in master due to
+privacy reasons of change-less transactions."
+
+Pieter Wuille asked, "So this is a bit of a question on what our coin
+selection algorithm should prioritize: confirmed coins or (immediate)
+fee [reduction]?"
+
+Sanders agreed and added, "and privacy.  [...] Change-less outputs mess
+with coin analysis to a large degree."
+
+Chow, and perhaps others, have performed simulations of the new
+behavior, the behavior from earlier versions of Bitcoin Core, and
+various alternatives.  The conversation then briefly discussed those
+results and what they implied, with at least two participants indicating
+they wanted to see more simulations performed.
+
+**Conclusion:** no explicit conclusion.  Chow is running more
+simulations and he, Wuille, and Sanders mentioned discussing them on the
+PR when they're available.
+
+## Mini-topics
+
+- Pieter Wuille said, "I have 4 PRs open relating to optimized hardware
+  SHA256.  Should I combine them into 1 [PR], or leave like this?
+  [#13471][], [#13386][], [#13442][], [#13438][]" Wladimir van der Laan
+  was opposed to [#13438][] being combined, and suggested it could be
+  merged soon, but neither Van der Laan nor anyone else offered comment
+  on whether or not the remaining PRs should be combined.
+
+- Regarding [#13442][], this PR introduced optimized code that initially
+  ran slower than before the optimization.  Its author, Wuille, has
+  since improved it to be faster, but he notes that it's "very heavily
+  compiler dependent: rearranging two lines can have 5% effect on speed,
+  or making a constant static, [...] or with particular GCC versions."
+  Van der Laan said, "If it becomes faster with new compilers, it's
+  good; if slower, not. :)"
+
+- Some brief discussion about managing release signatures for Bitcoin
+  Core 0.16.1.
+
+## Comic relief
+
+{% highlight text %}
+<ryanofsky> cd
+  <cfields> ~$
+{% endhighlight %}
+
+## Participants
+
+| IRC nick        | Name/Nym                  |
+|-----------------|---------------------------|
+| wumpus          | [Wladimir van der Laan][] |
+| sipa            | [Pieter Wuille][]         |
+| instagibbs      | [Gregory Sanders][]       |
+| achow101        | [Andrew Chow][]           |
+| cfields         | [Cory Fields][]           |
+| promag          | [Joao Barbosa][]          |
+| meshcollider    | [Samuel Dobson][]         |
+| luke-jr         | [Luke Dashjr][]           |
+| jonasschnelli   | [Jonas Schnelli][]        |
+| MarcoFalke      | [Marco Falke][]           |
+| jnewbery        | [John Newbery][]          |
+| kanzure         | [Bryan Bishop][]          |
+| ryanofsky       | [Russell Yanofsky][]      |
+
+## Disclaimer
+
+This summary was compiled without input from any of the participants in
+the discussion, so any errors are the fault of the summary author and
+not the discussion participants.  In particular, quotes taken from the
+discussion had their capitalization, punctuation, and spelling modified
+to produce consistent sentences.  Bracketed words and fragments, as well
+as background narratives and exposition, were added by the author of
+this summary and may have accidentally changed the meaning of some
+sentences.  If you believe any quote was taken out of context, please
+[open an issue](https://github.com/bitcoin-core/bitcoincore.org/issues/new)
+and we will correct the mistake.
+
+[bbm log]: https://botbot.me/freenode/bitcoin-core-dev/msg/101130091/
+
+[mb minutes]: http://www.erisian.com.au/meetbot/bitcoin-core-dev/2018/bitcoin-core-dev.2018-06-07-19.00.html
+[current high-priority PRs]: https://github.com/bitcoin/bitcoin/projects/8
+[instagibbs comment]: https://github.com/bitcoin/bitcoin/pull/13307#discussion_r192899180
+
+
+{% assign log = "http://www.erisian.com.au/meetbot/bitcoin-core-dev/2018/bitcoin-core-dev.2018-06-14-19.00.log.html" %}
+[mb log]: {{log}}
+[log hipri]: {{log}}#l-15
+[log srd]: {{log}}#l-58
+
+{% include link-to-issues.md issues="12136,13425,13111,13160,13439,13471,13386,13442,13438" %}