Add Accumulator: a striped long counter primitive as an alternative to LongAdder (perf toolbox) - #12351

Merged

gh-worker-dd-mergequeue-cf854d[bot] merged 38 commits into

dougqh/accumulator-primitive

Sep 22, 2026

Commits on Aug 31, 2026

Add Accumulator: a striped long counter primitive as an alternative to LongAdder

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c3def00
Oversize Accumulator's default stripe count to reduce contention collisions

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48e01bb
Add JOL footprint test: Accumulator vs one LongAdder per counter

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3629c97
Benchmark Accumulator against a per-counter-locked LongAdder alternative

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fc2f55c
Address review comments on Accumulator

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89d980c

Commits on Sep 1, 2026

Split Accumulator into a typed wrapper and a nested EmbeddingSupport

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7107b5b
Update Accumulator tests/benchmark for the EmbeddingSupport split

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Wrap Accumulator's update/accumulateAndReset in typed Stripe/Counts views

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c9f7fc2
Add benchmarks for Accumulator's typed API alongside raw EmbeddingSupport

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a8e7448
Record typed-vs-raw Accumulator benchmark results in AccumulatorBenchmark javadoc

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bf67e0b

Commits on Sep 2, 2026

Rename accumulatorAccumulateAnd* benchmarks, cap footprint test thread count

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3484ed7
Add a non-destructive Accumulator.sum() for live diagnostic reads
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Add Accumulator.Counts.plus() to combine a stored total with a live sum
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Add Accumulator.Counts.zero() to seed a running total without a scratch Accumulator

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93e2c2d
Add a contextual Accumulator.update(context, BiConsumer) overload

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34f1830
Let Counts expose its own keys and add Class<E>-based factories

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8df6143
Rename Counts.values() to Counts.keys()

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9bc7abc
Add Accumulator.update(long, ObjLongConsumer) to avoid boxing a primitive context
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7e80a21
Only touch the real counter width in combine/reset, not the padded stripe row
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69251a5
Replace Accumulator's synchronized stripes with lock-free AtomicLongArray striping

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baf0a33
Correct AccumulatorBenchmark javadoc's high-contention drain numbers

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e90422c

Commits on Sep 3, 2026

Add fair per-thread-distributed 8-wide AccumulatorBenchmark comparison, correct javadoc numbers
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065ee24

Commits on Sep 10, 2026

Remove Accumulator.of(E[])/Counts.zero(E[]) in favor of the Class<E> factory
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b90e7f6
Add unstriped AtomicLongArray baseline to AccumulatorBenchmark
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Add Accumulator.RunningTotal, an opt-in drain+live-read composition

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f28a67a
Rename Accumulator/Counts field values -> keys

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631edde
Move Accumulator from internal-api into metrics-api, next to Counter

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8e6e624
Mark Accumulator/RunningTotal @ThreadSafe; add Counts.from(fromIndex)

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b3075db
Add StatsDCountReporter: an Accumulator-backed periodic statsd reporter with retry

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108ce69
Return an unmodifiable List view from Counts.keys() instead of the shared array

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Cap Accumulator's stripe count at 64 regardless of core count

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a60d97c

Commits on Sep 11, 2026

Refresh AccumulatorBenchmark javadoc results after the stripe-count cap

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2fe50b1
Run AccumulatorVsCounterBenchmark with a real client, not a true no-op

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300ca8d
Rename Counts.zero() to Counts.create()

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aae3a54
Add fair single-counter LongAdder-delta baseline to AccumulatorBenchmark

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Note AccumulatorVsCounterBenchmark's LockingStatsDClient as a conservative lower bound

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e9cc2de

Commits on Sep 15, 2026

Merge branch 'master' into dougqh/accumulator-primitive
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48704bb

Commits on Sep 21, 2026

Merge remote-tracking branch 'origin/master' into dougqh/accumulator-primitive-local
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4be76af