@ -146,6 +146,68 @@ HD wallets are incompatible with older versions of Bitcoin Core.
@@ -146,6 +146,68 @@ HD wallets are incompatible with older versions of Bitcoin Core.
[Pull request ](https://github.com/bitcoin/bitcoin/pull/8035/files ), [BIP 32 ](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki )
Segregated Witness
------------------
The code preparations for Segregated Witness ("segwit"), as described in [BIP
141](https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki), [BIP
143](https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki), [BIP
144](https://github.com/bitcoin/bips/blob/master/bip-0144.mediawiki), and [BIP
145](https://github.com/bitcoin/bips/blob/master/bip-0145.mediawiki) are
finished and included in this release. However, BIP 141 does not yet specify
activation parameters on mainnet, and so this release does not support segwit
use on mainnet. Testnet use is supported, and after BIP 141 is updated with
proposed parameters, a future release of Bitcoin Core is expected that
implements those parameters for mainnet.
Furthermore, because segwit activation is not yet specified for mainnet,
version 0.13.0 will behave similarly as other pre-segwit releases even after a
future activation of BIP 141 on the network. Upgrading from 0.13.0 will be
required in order to utilize segwit-related features on mainnet (such as signal
BIP 141 activation, mine segwit blocks, fully validate segwit blocks, relay
segwit blocks to other segwit nodes, and use segwit transactions in the
wallet, etc).
Mining transaction selection ("Child Pays For Parent")
------------------------------------------------------
The mining transaction selection algorithm has been replaced with an algorithm
that selects transactions based on their feerate inclusive of unconfirmed
ancestor transactions. This means that a low-fee transaction can become more
likely to be selected if a high-fee transaction that spends its outputs is
relayed.
With this change, the `-blockminsize` command line option has been removed.
The command line option `-blockmaxsize` remains an option to specify the
maximum number of serialized bytes in a generated block. In addition, the new
command line option `-blockmaxweight` has been added, which specifies the
maximum "block weight" of a generated block, as defined by [BIP 141 (Segregated
Witness)] (https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki).
In preparation for Segregated Witness, the mining algorithm has been modified
to optimize transaction selection for a given block weight, rather than a given
number of serialized bytes in a block. In this release, transaction selection
is unaffected by this distinction (as BIP 141 activation is not supported on
mainnet in this release, see above), but in future releases and after BIP 141
activation, these calculations would be expected to differ.
For optimal runtime performance, miners using this release should specify
`-blockmaxweight` on the command line, and not specify `-blockmaxsize` .
Additionally (or only) specifying `-blockmaxsize` , or relying on default
settings for both, may result in performance degradation, as the logic to
support `-blockmaxsize` performs additional computation to ensure that
constraint is met. (Note that for mainnet, in this release, the equivalent
parameter for `-blockmaxweight` would be four times the desired
`-blockmaxsize` . See [BIP 141]
(https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki) for additional
details.)
In the future, the `-blockmaxsize` option may be removed, as block creation is
no longer optimized for this metric. Feedback is requested on whether to
deprecate or keep this command line option in future releases.
Removal of internal miner
--------------------------
Wladimir J. van der Laan
8 years ago