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fix(npmjs): follower cannot recover from large scan backlogs - #1938
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cdklabs-automation merged 2 commits intoSep 24, 2026
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After an outage or crash period, the unreceipted backlog can be larger than what fits into a single execution. Runs then die at the Lambda timeout, which is a hard kill: the end-of-run state save never executes, so every run restarts the same backlog from scratch and the follower never recovers. Gamma live-locked this way for a day with a 24h backlog. The scan now processes unreceipted entries in chunks of 1,000 and persists the state (receipts, checkpoints, laggy packuments, known versions) after every chunk. The time budget is re-checked between chunks, so runs exit cleanly before the timeout, and even a hard kill only loses the current chunk. Each run banks its progress and the backlog drains across runs.
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After deploying #1937 our environment is still stuck. The state file hadn't been saved for 24 hours because of the crashes, so the follower has a backlog of roughly 250k entries without receipts. That is more work than fits into one execution. Runs hit the Lambda timeout, and on a timeout Lambda kills the process without running the
finallyblock. So the state was never saved, and the next run started over with the same backlog.We can fix this:
The scan now processes entries in chunks of 1,000 and saves the state (receipts, checkpoints, laggy packuments, known versions) after every chunk. If a run is killed, only the current chunk is lost. Progress is kept between runs and the backlog shrinks until it's gone. The time budget is now also checked between chunks.
Previously these checkpoints were only run after a full page, which can be up to 10k changes. During a catch-up a most entries will be without receipts, and processing them can take longer than the whole execution.
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