The Bitcoin Core team published the next release of its client - 0.15.0. Version 0.15.0 currently exists as RC1 (Release Candidate 1) and is not yet available for download from the official site, but RC1 for all operating systems can already be downloaded to GitHub. Publication of the release is expected in the coming days.
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Below are the most notable changes that appeared in the new release. Version 0.15.0 contains a number of significant performance improvements that accelerate the initial synchronization of the block (IBD), start, transaction and block checking:
The chainstate database (which is used to track UTXO, the table of "unspent outputs") has been changed from the model for each transaction to the model for each output, which will allow optimizing many processes, such as using a memule, adapting to various cache cleaning strategies, and also avoiding Increased load on the CPU (CPU).
In Bitcoin Core 0.15.0, the memory usage for UTXO is calculated more accurately - all available cache (dbcache) is now actually used in its entirety, which reduces the cache clearing frequency by a factor of 2.In addition, the time for testing new blocks is accelerated by 40-50% due to improved caching when checking transactions during admission to the mem- pule.The LevelDB database has been updated to version 1.20 - as a result, synchronization and block checking are now faster.
Bitcoin Core 0.15.0 has improved the algorithm for calculating commissions, which now contains a wider range of options. Internal assessments are now monitored on three different time horizons. This allows the use of longer targets and average scores to adapt more quickly to changes in conditions.
Now estimates can be conservative or economical. Conservative estimates use longer time horizons for settlement, the commission is less susceptible to rapid changes in payment terms. Economical estimates use shorter time horizons and will be more susceptible to short-term changes in payment terms. Economic estimates can be significantly lower in periods of low transaction activity (for example, over the weekend), but may lead to transactions that remain unconfirmed if commissions grow.
Also changed the RPC interface for commissions. Added a new RPC evaluation to provide raw payment data. Customers can request and use this data in their own logic for calculating commissions.Bitcoin Core 0.15.0 now supports the downloading of several individual wallets with individual balances, keys and received transactions.
The new version removes the remnants of the so-called priority support of coins (part of each block could be reserved for transactions depending on the age and cost of UTXO that the miners spent). In addition, BitcoinCore 0.15.1 eliminated previous minor errors and introduced some optimizations. The complete list of changes in Bitcoin Core 0.15.0 is traditionally published on Github.