fix: don't keep the startup finalized block pinned forever - #2266
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marian-radu
commented
Jul 31, 2026
lexnv
reviewed
Aug 3, 2026
| // subscription would see. | ||
| shared | ||
| .block_events_for_new_subscriptions | ||
| .retain(|e| !matches!(e, FollowEvent::BestBlockChanged(_))); |
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Thanks! It makes sense, this effectively cleans up the block_events_for_new_subscriptions. If we had:
- new block 1 + bestBlock 1 + new Block 2 + bestBlock 2
- new subscribers would see: new block 1 + new block 2 + best block 2
lexnv
approved these changes
Aug 3, 2026
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Problem
FollowStreamDriver's replay buffer holdsBlockRefs and entries only leave it when a laterFinalizedevent reports the block.At subscription start the node unconditionally reports the current best block. When best == finalized, always on instant-seal, a connect-time race otherwise, that block was finalized before we started watching, so no
Finalizedevent we receive ever reports it and the pin lasts for the life of the subscription, so the node can't prune state past that block.Fix
Keep only the latest
BestBlockChangedin the buffer. This behavior matches the node rather than diverging from it.Subscribers joining mid-stream now receive only the latest best-block event. Existing subscribers are unaffected.
Testing
startup_best_block_event_is_not_kept_alive_foreverasserts the replay buffer no longer references block 0 and that an unpin was issued for it.