High level summary
The consensus team is resuming its activities after the Christmas break. During these weeks we focused on cleaning and benchmarking the UTxO-HD prototype, and discussing with the Ledger team the changes that might be required for the next iterations. The pull request that adds the Conway era is waiting for a second review round and we hope to merge it soon. On the technical debt side we are looking into a property-test failure found in the iterators. We are investigating if this is an error in the model or in the implementation. We also improved the documentation of our testing code.
Workstreams
UTxO HD Prototype
We worked with the Ledger team to start preparing the next versions of UTxO-HD. The Ledger team is concerned that for the remaining maps we might need the full ledger state on epoch boundaries. Since the main consumer of the ledger rules is Consensus, the code that requires access to a full state could be moved from the ledger to some Ledger-Consensus bridge. Eg. the traversal of rewards could take place in such bridge, instead of querying the ledger for the values that are required in the epoch-transition computations.
We relocated some UTxO-HD definitions, in preparation for merging
the prototype into master.
We also completed updated local benchmarks comparing the replay time and memory consumption of:
- the baseline node (
f2fc76ef45647275c98634da1718290b976ff364) - the UTxO-HD node with the in-memory backend
- the UTxO-HD node with the LMDB backend
The following plot shows the results: we can see that the LMDB node barely
reaches 8GB of memory, but it takes 1.78 times longer to replay the chain. The
in-memory backend is about 30 minutes faster, but still slower than the baseline
version. We are aware of this phenomenon and it is inherent to the problem of
maintaining sequences of differences of the last k ledger states that allows
us to perform rollback and roll-forward. We are in the process of measuring
syncing from scratch times.
We also added StaticEither accessors that helped us to simplify
the UTxO-HD prototype.
New Conway era
We incorporated the feedback of the pull request, and rebased this
branch on top of master. The PR is pending a second review round and we hope
to merge this soon.
Technical debt
We are investigating a property-testing failure involving
iterators. Solving this requires understanding the expected behavior of
iterators in the counterexample found by QuickCheck to determine if the error
is in the model or in the implementation.
Fostering collaboration
We moved the contents of docs/Testing.md closer to the code, so that the
explanations about the tests are easier to find in the relevant modules, and the
documentation is easier to keep up to date.