Release notes

Version 0.3

5x performance increase

We acheived a roughly 5x performance increase (for the C++ interface) at the cost of a small (under 4%) increase in memory consumption. BlockSci can now iterate over every transaction input and output on the Bitcoin blockchain in about 1 second on a single 4-core EC2 instance. Most of the improvements came from improving memory alignment in data files.

In our paper we presented performance results for iterating over transactions using the C++ library (up to block 478,449 of the Bitcoin blockchain). In the table below we compare the timings reported in the paper (Old) to the corresponding timings for version 0.3 (New).

Iterating over Single Threaded Multithreaded
Old New Old New
Transaction headers 13.1 sec 3.0 sec 3.2 sec 0.6 sec
Transaction outputs 27.9 sec 3.4 sec 6.6 sec 0.9 sec
Transaction inputs & outputs 46.4 sec 4.2 sec 10.3 sec 1.1 sec
Headers in random order 303.0 sec 99.9 sec Unsupported Unsupported

In future versions we plan to bring the Python performance for most common types of queries closer to the C++ performance figures in the table.

New data format

As noted above, we updated the data format. This requires rerunning the parser from scratch if you are running a local copy of BlockSci. If you are using the EC2 AMI image you can simply launch a new server with the BlockSci 0.3 image.

SegWit support & API changes

  • We provide full support to two new address types (Pay to Witness Script Hash and Pay to Witness Pubkey Hash)

  • New distinction between address type and script type

    Version 0.3 introduces a distinction between two outputs which are sent the same way and two outputs that can be spent using the same information. This difference comes up in multiple circumstances including when a the same public key is used is a pay to public key hash output and inside a multisignature output.

    Inside the BlockSci interface these two related concepts map to the Address and Script types respectively. Both objects possess very similar APIs, but operate somewhat differently. As an example, given a specific P2PKH address, address, the then address.outs() will return all outputs sent to that specific address. If the pubkey used in that address was also used in another type of output, this would not be shown. However calling address.script.outs() will return all outputs where that pubkey was used in any form.

    Additionally Script objects contain a large amount of information about the script used. For instance Multisig scripts provide access to all the pubkeys involved and P2SH scripts provide access to the wrapped address if it is known.

  • Moved heuristic-based behavior to a separate module (blocksci.heuristics) to make it easier to distinguish it from core functionality.

    The heuristics library contains two main types of heuristics: change address identification and transaction labeling. In the previous version these functionalities were included in the main functionality of the library making it difficult to distinguish between functions which are guaranteed to be correct and functions which only produce guesses.

    New versions of the API are accessable by using

    blocksci.heuristics.change_by_client_change_address_behavior(tx)
blocksci.heuristics.is_coinjoin(tx)

Additional index lookup

We have added an index to allow the lookup of transactions by hash and addresses by address string.

Transactions can be looked up via blocksci.Tx(hash_string) and addresses can be looked up via blockcsi.Address.from_string(address_string).

Bug fixes

  • Many causes of crashes and instability have now been resolved.
  • Segwit support has been introduced. (Issue #1)
  • The address index lookups now will return correct results. (Issue #6)
  • The parser no longer reads beyond memory boundaries causing occasional crashes. (Issue #9)
  • The initial header parse phase is now multithreaded leading to a substantial performance increase. (Issue #12)
  • Fixed bitcoin-api-cpp headers so it now works on both mac and linux. (Issue #15)
  • The parser now provides feedback as it goes. (Issue #26)
  • The python module no longer crashes on exit. (Issue #25)

Limitations

Incremental updating of the blockchain is currently not supported due to some continuing bugs in blockchain reorg handling. Rerunning the parser in the uncommon situation that a previously parsed block has been orphaned may cause data corruption.

Version 0.2

This version was the initial release of BlockSci. Documentation for version 0.2 is still available.