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Consensus Team Update

· 2 min read
Damian Nadales

High level summary

During the past two weeks, the consensus team worked on improving the performance of the ChainSync jumping logic, which is needed for Genesis. We also rewrote the implementation of the mempool in the UTxO HD prototype which solved the issues that prevented us from running system level benchmarks. Also on the UTxO HD front, we have an improved implementation of the sequence-of-differences (a crucial piece of UTxO HD), and we also elaborated a test sign-off list for the UTxO HD feature.

Executive summary

  • With the latest implementation of ChainSync jumping we are closer to the baseline performance. In particular, the prototype seems to benefit from the extra concurrency provided by additional capabilities.
  • We rewrote the implementation of the mempool in the UTxO HD prototype. This rewrite was required due to performance problems we observed when running the workbench. These performance problems prevented us from running system level benchmarks. The rewrite solved these issues. After the UTxO-HD: mempool rewrite PR is merged, we will contact the Benchmarking team so that they run the system level benchmarks.
  • The implementation of sequences of differences based on anti-diffs was integrated into the UTxO HD prototype. It is pending review and we also need to run replay and syncing benchmarks to confirm that this will deliver a performance improvement, as observed in our micro-benchmarks.
  • The UTxO HD prototype inspection resulted in a list of tests needed for consensus to consider the UTxO HD prototype as fully tested.

Additional information


Benchmarking setup: 50MBit/s, 50ms latency

  • Red: baseline
  • Green: Current CSJ prototype, 10 peers, jumps every 3000/f slots.

As ChainSync Jumping involves many concurrent network operations at every jump, we tried to run the node with 6 instead of the default 2 capabilties.

  • Orange: baseline with 6 capabilities
  • Blue: CSJ prototype with 6 capabilities

This diagram shows the respective syncing progress, starting at Genesis and continuing a good part into Shelley (with the dashed line indicating the Byron-to-Shelley transition).

Further work includes whether we can tune the prototype to better handle few capabilities, or to adapt the default number of capabilities (potentially just while syncing).