[Perf] Faster block tree (de)serialization - #3349
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Signed-off-by: ljedrz <ljedrz@users.noreply.github.com>
Signed-off-by: ljedrz <ljedrz@users.noreply.github.com>
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Found while working on ProvableHQ/snarkOS#4361: restarting the nodes took way longer than I anticipated, and it boils down to a flat ~48s (on my machine, ~125s in the CI) cost of loading the block tree cache, which - while still a big improvement for very large ledgers - is a slowdown for small ones.
This PR removes this flat (de)serialization "tax", by introducing a
MerkleTreeStateobject, which is a subset of theMerkleTree, sans its hashers, which can be recreated without having to deserialize them from the cache file.Below is a comparison of the block tree load times between the current state and this PR:
Why haven't we noticed this sooner? Variable window size was added to BHP on 30.04.2026 (dd09be7, efa368b), along with setup and size metrics, which increased the size of the serialized block tree from ~210KiB to 20.7MiB, so what originally cost ~0.5s to deserialize now costs ~48s. Note: those changes were most likely expected, and have their own benefits, with this fallout just being an expected side effect.