consensus/istanbul: bound backlog and ROUND CHANGE retention - #1053
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consensus/istanbul: bound backlog and ROUND CHANGE retention#1053da1suk8 wants to merge 2 commits into
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Limit retained future messages per sender and globally by count and payload size. Reject distant future sequences and release backlog accounting when messages leave.
Retain only a bounded future-round window and a quorum of distinct senders per round. Reject rounds that cannot be represented by the bucket key.
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August 27, 2026 05:08
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August 27, 2026 05:08
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Proposed changes
Adds retention limits to the Istanbul future-message backlog and to
roundChangeSet, so that memory used for retained messages stays boundedregardless of traffic.
(1024 messages / 128 MiB).
the accounting and queue storage once a sender's messages are processed or
discarded.
requiredMessageCountdistinct senders per round bucket.Trace, since they are expected under load.Byte accounting is used alongside message counts because a PREPREPARE carries an
entire block, so a count-only limit does not bound memory.
The quorum and wire protocol are unchanged.
Types of changes
Checklist
I have read the CLA Document and I hereby sign the CLAin first time contribute after having read CLA$ make test)Related issues
Complements #1029, which bounds Istanbul message ingress concurrency rather than
retained message memory.
Further comments
Distant ROUND CHANGE entries are rejected rather than evicting retained round
buckets, so that the near-round buckets needed for catch-up are kept. This
intentionally trades catch-up beyond the round window for bounded memory.
Nodes that are behind the backlog sequence window recover through block
synchronization.