Stop repeatedly syncing from peers that don't extend our best chain - #476
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🟡 Changes recommended
Partial heavier forks can be suppressed, and concurrent relay notifications can be lost.
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What changed in this PR
Prevents repeated downloads from peers whose fork batches do not advance the local best chain.
Changes:
- Marks non-advancing peers as synced.
- Adds fork and multi-batch synchronization tests.
- Documents the bandwidth fix in a changeset.
| File | Description |
|---|---|
syncer/syncer.go |
Detects unchanged tips after synchronization. |
syncer/syncer_test.go |
Tests fork suppression and continued useful syncing. |
.changeset/stopped_repeatedly_syncing_from_peers_whose_blocks_do_not_extend_our_best_chain.md |
Records the user-facing fix. |
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🟡 Changes recommended
Legacy difficulty calculations use an invalid timestamp, and the implementation can retain unbounded header batches across peers.
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Historical difficulty calculation and peer-chain race conditions can cause incorrect synchronization decisions or stalled peers.
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Critical replay validation and several consensus-state and timeout issues remain unresolved.
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The tests do not compile, and header-state calculation may misclassify peer chain work.
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Nick has reported excessive bandwidth usage from the syncer and shared his logs with us.
In 15 hours or so his node downloaded a few hundred thousand blocks from peers that seem to be stuck on a different fork. So syncing with them doesn't actually extend our best chain. We end up syncing the same batch of blocks every 5 seconds because
r.remainingnever reaches0.The implemented solution is to check if a peer's chain is more heavy than our own based off the headers rather than fetching actual blocks.