IRC meeting summary for 2016-04-21


Main topics

  • Segwit review
  • Travis switch to trusty

Segwit review


Developers are working on a soft fork to introduce segregated witness onto Bitcoin mainnet, with initial testing being performed on a special testnet. Segregated witness (segwit) allows transaction signature data to be stored outside of the data hashed to produce transaction identifiers, removing all known forms of third-party malleability, allowing full nodes to compile the current UTXO set without downloading all signatures, and laying the groundwork for fraud proofs that can allow lightweight (SPV) clients to help enforce more of the consensus rules. The segwit soft fork also allows miners to substitute 1 byte of block space with 4 bytes of segwit data, increasing transaction capacity for wallets that use segwit. segregated witness BIPs: BIP141, BIP142, BIP143, BIP144 and BIP145

meeting comments

There has been a lot of input for the segwit implementation PR #7910, which was made last week. Morcos and sdaftuar propose to all make an effort to review segwit and delay other merging as much as possible. Gmaxwell and wumpus note this will create an artificial pressure to merge segwit and there are too many other things going on to delay everything. Wumpus does agree we should delay PR’s that potentially conflict with segwit, like consensus and relay policy refactors. Sipa notes he’s not very worried about anything that’s in progress right now.

There are some safe preparation commits/PR’s that should go in first, those should be a priority.
A lot of developers want some more info on which areas are getting a lot of testing, which are not, which areas are critical and need extra attention, which areas need to be prioritized, etc. in order to smooth the review process.

meeting conclusion

  • More code review of segwit
  • Luke-jr needs to update PR #7935 getblocktemplate support for versionbits.

Travis switch to trusty


Travis is an open source continuous integration (CI) service used to build and test software projects hosted at GitHub. Bitcoin Core has planned to start using C++11 in 0.13 and thus would require an updated version of Travis to build and test pull requests. This version called ‘trusty’ is currently in beta. Bitcoin Core has gotten a flag from the Travis team to use the caching function, which is not available by default yet.

meeting comments

Cfields, who’s working on the C++11 update, notes that there might be a few hours of instability when switching to trusty as the flag comes with the caveat of invalidating all current caches.

A few developers fail to enable travis for their own repository or have it fail.

There is an option of adding another github compatible CI service to speed up tests, however that would mean more maintenance which is probably not worth it.

meeting conclusion

Merge PR #7920 when cfields gives the green light.

Comic relief

<wumpus>   ok, any other topics to be discussed?
<btcdrak>  the segwit afterparty!


IRC nick Name/Nym
btcdrak BtcDrak
gmaxwell Gregory Maxwell
jonasschnelli Jonas Schnelli
Morcos Alex Morcos
sipa Pieter Wuille
wumpus Wladimir van der Laan
kanzure Bryan Bishop
sdaftuar Suhas Daftuar
CodeShark Eric Lombrozo
cfields cory Fields
Luke-jr Luke Dashjr
jtimon Jorge Timon


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.

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