Andrew Noyes
cce7d29410
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weaselab/conflict-set/pipeline/head There was a failure building this commit
108 lines
3.8 KiB
Markdown
108 lines
3.8 KiB
Markdown
A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys.
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Intended to replace FoundationDB's skip list.
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Hardware for all benchmarks is a mac m1 2020.
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# FoundationDB's benchmark
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## Skip list
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```
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New conflict set: 1.957 sec
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0.639 Mtransactions/sec
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2.555 Mkeys/sec
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Detect only: 1.845 sec
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0.678 Mtransactions/sec
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2.710 Mkeys/sec
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Skiplist only: 1.263 sec
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0.990 Mtransactions/sec
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3.960 Mkeys/sec
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Performance counters:
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Build: 0.0546
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Add: 0.0563
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Detect: 1.84
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D.Sort: 0.412
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D.Combine: 0.0141
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D.CheckRead: 0.671
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D.CheckIntraBatch: 0.0068
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D.MergeWrite: 0.592
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D.RemoveBefore: 0.146
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```
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## Radix tree (this implementation)
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```
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New conflict set: 1.366 sec
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0.915 Mtransactions/sec
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3.660 Mkeys/sec
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Detect only: 1.248 sec
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1.002 Mtransactions/sec
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4.007 Mkeys/sec
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Skiplist only: 0.573 sec
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2.182 Mtransactions/sec
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8.730 Mkeys/sec
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Performance counters:
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Build: 0.0594
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Add: 0.0572
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Detect: 1.25
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D.Sort: 0.418
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D.Combine: 0.0149
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D.CheckRead: 0.232
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D.CheckIntraBatch: 0.0067
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D.MergeWrite: 0.341
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D.RemoveBefore: 0.232
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```
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# Our benchmark
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## Skip list
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| ns/op | op/s | err% | total | benchmark
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|--------------------:|--------------------:|--------:|----------:|:----------
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| 256.89 | 3,892,784.92 | 0.3% | 0.01 | `point reads`
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| 272.90 | 3,664,395.04 | 0.2% | 0.01 | `prefix reads`
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| 507.22 | 1,971,549.50 | 0.7% | 0.01 | `range reads`
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| 452.66 | 2,209,181.91 | 0.5% | 0.01 | `point writes`
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| 438.09 | 2,282,619.96 | 0.4% | 0.01 | `prefix writes`
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| 253.33 | 3,947,420.36 | 2.5% | 0.02 | `range writes`
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| 574.07 | 1,741,936.71 | 0.3% | 0.01 | `monotonic increasing point writes`
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| 151,562.50 | 6,597.94 | 1.5% | 0.01 | `worst case for radix tree`
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## Radix tree (this implementation)
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| ns/op | op/s | err% | total | benchmark
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|--------------------:|--------------------:|--------:|----------:|:----------
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| 19.83 | 50,420,955.28 | 0.1% | 0.01 | `point reads`
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| 55.95 | 17,872,542.40 | 0.5% | 0.01 | `prefix reads`
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| 88.28 | 11,327,709.50 | 0.4% | 0.01 | `range reads`
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| 29.15 | 34,309,531.64 | 0.5% | 0.01 | `point writes`
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| 42.36 | 23,607,424.27 | 1.1% | 0.01 | `prefix writes`
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| 50.00 | 20,000,000.00 | 0.0% | 0.01 | `range writes`
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| 93.52 | 10,692,413.79 | 3.3% | 0.01 | `monotonic increasing point writes`
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| 2,388,417.00 | 418.69 | 0.4% | 0.03 | `worst case for radix tree`
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# "Real data" test
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Point queries only, best of three runs. Gc ratio is the ratio of time spent doing garbage collection to time spent adding writes or doing garbage collection. Lower is better.
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## skip list
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```
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Check: 11.3385 seconds, 329.718 MB/s, Add: 5.35612 seconds, 131.072 MB/s, Gc ratio: 45.7173%
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```
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## radix tree
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```
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Check: 2.48583 seconds, 1503.93 MB/s, Add: 2.12768 seconds, 329.954 MB/s, Gc ratio: 41.7943%
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```
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## hash table
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(The hash table implementation doesn't work on range queries, and its purpose is to provide an idea of how fast point queries can be)
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```
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Check: 1.83386 seconds, 2038.6 MB/s, Add: 0.601411 seconds, 1167.32 MB/s, Gc ratio: 48.9776%
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```
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