Andrew Noyes
3c100ccee8
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106 lines
3.6 KiB
Markdown
106 lines
3.6 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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| 246.99 | 4,048,700.59 | 0.2% | 0.01 | `point reads` |
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| 260.16 | 3,843,784.65 | 0.1% | 0.01 | `prefix reads` |
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| 493.35 | 2,026,953.19 | 0.1% | 0.01 | `range reads` |
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| 462.05 | 2,164,289.23 | 0.6% | 0.01 | `point writes` |
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| 448.19 | 2,231,205.25 | 0.9% | 0.01 | `prefix writes` |
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| 255.83 | 3,908,845.72 | 1.5% | 0.02 | `range writes` |
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| 582.63 | 1,716,349.02 | 1.3% | 0.01 | `monotonic increasing point writes` |
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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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| 19.42 | 51,483,206.67 | 0.3% | 0.01 | `point reads` |
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| 58.43 | 17,115,612.57 | 0.1% | 0.01 | `prefix reads` |
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| 216.09 | 4,627,766.60 | 0.2% | 0.01 | `range reads` |
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| 28.35 | 35,267,567.72 | 0.2% | 0.01 | `point writes` |
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| 43.43 | 23,026,226.17 | 0.2% | 0.01 | `prefix writes` |
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| 50.00 | 20,000,000.00 | 0.0% | 0.01 | `range writes` |
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| 92.38 | 10,824,863.69 | 4.1% | 0.01 | `monotonic increasing point writes` |
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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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