db/snapshotsync/freezeblocks: run block-snapshot merge off the shared build semaphore#21526
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db/snapshotsync/freezeblocks: run block-snapshot merge off the shared build semaphore#21526sudeepdino008 wants to merge 1 commit into
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… build semaphore Block retire held the shared snapshot-build semaphore across both the dump and the slow, expensive merge, blocking state-snapshot collation/prune for the merge's full duration. Release the semaphore after the dump and run the merge in its own goroutine (mirroring the aggregator's MergeLoop). The fast dump stays serialized against state building; the slow merge no longer starves state collation.
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Problem
Block retirement holds the shared snapshot-build semaphore (
snBuildAllowed, default size 1) across both the fast dump and the slow, expensive block-segment merge. While a large block merge runs, state-snapshot collation/prune (which bounds chaindata growth) is blocked for the merge's full duration.Observed on a minimal node: an 8.2 GB / ~19-minute
025100→025200transactions merge held the semaphore the whole time, starving state collation —stepsInDBclimbed to 3.82 (chaindata bloats while collation waits).Change
Release the semaphore after the dump phase and run the merge in its own goroutine, off the semaphore — mirroring how the aggregator runs
MergeLoop. The fast dump stays serialized against state-snapshot building (preserving the I/O-throttle intent); the slow merge no longer starves state collation.Effect
With the same 8.2 GB block-tx merge in flight, state collation now proceeds concurrently —
stepsInDBstays < 2 (was 3.82). The CLIretirepath callsMergeBlocksexplicitly so its behavior is unchanged.Tests
TestBlockMergeRunsWithoutSemaphore— merge completes while the semaphore is fully held (regression-guards re-acquisition).TestRetireBlocksInBackgroundReleasesSemaphore— background retire releases the semaphore, no leak.Draft — full
make lint+ integration verification pending.