MassivePizza opened a new pull request, #10364:
URL: https://github.com/apache/arrow-rs/pull/10364
# Which issue does this PR close?
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N/A
# Rationale for this change
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the issue then this section is not needed.
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changes and offer better suggestions for fixes.
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Converting decimals and FixedLenByteArrays to individual allocs requires a
lot of alloc+drop time and memory overhead.
# What changes are included in this PR?
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There is no need to duplicate the description in the issue here but it is
sometimes worth providing a summary of the individual changes in this PR.
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Allocate one big buffer, and cut it up into slices of `bytes::Bytes`. This
amortizes the alloc upfront, and effectively eliminates the drop overhead by
turning a dealloc to an Arc decrement per slice.
This still has moderate memory overhead. `Bytes` is 32 bytes, while the
slices usually expose less than 16 bytes at a time e.g. UUIDs or decimal128,
but a lot more effort would be required to implement a (perhaps borrowed?)
alternative that behaves like `FixedLenByteArray`.
There are a few other ideas worth exploring, primarily custom
`ColumnValueEncoder`s that converts on the fly to avoid the temporary allocs
all together.
# Are these changes tested?
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2. Serve as another way to document the expected behavior of the code
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they covered by existing tests)?
If this PR claims a performance improvement, please include evidence such as
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Should be covered by existing tests. There are also new benches included:
<details>
<summary>decimal bench</summary>
```
Benchmarking decimal/default: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 5.4s, or reduce sample count to 90.
decimal/default time: [53.676 ms 53.979 ms 54.306 ms]
thrpt: [1.0790 GiB/s 1.0855 GiB/s 1.0916 GiB/s]
change:
time: [−44.611% −44.247% −43.885%] (p = 0.00 <
0.05)
thrpt: [+78.204% +79.362% +80.542%]
Performance has improved.
Found 5 outliers among 100 measurements (5.00%)
4 (4.00%) high mild
1 (1.00%) high severe
Benchmarking decimal/bloom_filter: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 6.8s, or reduce sample count to 70.
decimal/bloom_filter time: [66.597 ms 66.838 ms 67.095 ms]
thrpt: [894.26 MiB/s 897.70 MiB/s 900.94 MiB/s]
change:
time: [−40.229% −39.907% −39.555%] (p = 0.00 <
0.05)
thrpt: [+65.440% +66.408% +67.306%]
Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
8 (8.00%) high mild
2 (2.00%) high severe
Benchmarking decimal/parquet_2: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 10.8s, or reduce sample count to 40.
decimal/parquet_2 time: [105.82 ms 106.23 ms 106.66 ms]
thrpt: [562.52 MiB/s 564.84 MiB/s 567.02 MiB/s]
change:
time: [−48.804% −48.523% −48.229%] (p = 0.00 <
0.05)
thrpt: [+93.160% +94.263% +95.329%]
Performance has improved.
Found 3 outliers among 100 measurements (3.00%)
2 (2.00%) high mild
1 (1.00%) high severe
Benchmarking decimal/zstd: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 6.4s, or reduce sample count to 70.
decimal/zstd time: [61.806 ms 62.013 ms 62.282 ms]
thrpt: [963.36 MiB/s 967.55 MiB/s 970.78 MiB/s]
change:
time: [−60.257% −59.907% −59.556%] (p = 0.00 <
0.05)
thrpt: [+147.25% +149.42% +151.62%]
Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
1 (1.00%) low severe
2 (2.00%) low mild
5 (5.00%) high mild
3 (3.00%) high severe
Benchmarking decimal/zstd_parquet_2: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 11.9s, or reduce sample count to 40.
decimal/zstd_parquet_2 time: [119.51 ms 119.87 ms 120.29 ms]
thrpt: [498.82 MiB/s 500.54 MiB/s 502.07 MiB/s]
change:
time: [−55.716% −55.352% −54.992%] (p = 0.00 <
0.05)
thrpt: [+122.18% +123.98% +125.82%]
Performance has improved.
Found 11 outliers among 100 measurements (11.00%)
2 (2.00%) low mild
2 (2.00%) high mild
7 (7.00%) high severe
Benchmarking decimal/cdc: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase
target time to 7.8s, or reduce sample count to 60.
decimal/cdc time: [77.810 ms 78.092 ms 78.389 ms]
thrpt: [765.42 MiB/s 768.33 MiB/s 771.11 MiB/s]
change:
time: [−35.689% −35.360% −35.011%] (p = 0.00 <
0.05)
thrpt: [+53.873% +54.703% +55.494%]
Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
10 (10.00%) high mild
```
</details>
<details>
<summary>fsb bench</summary>
```
fsb/default time: [5.4152 ms 5.4276 ms 5.4407 ms]
thrpt: [2.8943 GiB/s 2.9013 GiB/s 2.9079 GiB/s]
change:
time: [−27.824% −27.512% −27.215%] (p = 0.00 <
0.05)
thrpt: [+37.391% +37.953% +38.550%]
Performance has improved.
Found 7 outliers among 100 measurements (7.00%)
1 (1.00%) low mild
5 (5.00%) high mild
1 (1.00%) high severe
fsb/bloom_filter time: [5.8681 ms 5.8908 ms 5.9154 ms]
thrpt: [2.6621 GiB/s 2.6732 GiB/s 2.6835 GiB/s]
change:
time: [−25.701% −25.298% −24.896%] (p = 0.00 <
0.05)
thrpt: [+33.148% +33.866% +34.592%]
Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
3 (3.00%) high mild
3 (3.00%) high severe
fsb/parquet_2 time: [8.6936 ms 8.7692 ms 8.8503 ms]
thrpt: [1.7793 GiB/s 1.7957 GiB/s 1.8113 GiB/s]
change:
time: [−31.621% −31.005% −30.286%] (p = 0.00 <
0.05)
thrpt: [+43.444% +44.939% +46.243%]
Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
9 (9.00%) high mild
1 (1.00%) high severe
fsb/zstd time: [7.1760 ms 7.2043 ms 7.2360 ms]
thrpt: [2.1762 GiB/s 2.1858 GiB/s 2.1944 GiB/s]
change:
time: [−21.480% −21.068% −20.631%] (p = 0.00 <
0.05)
thrpt: [+25.994% +26.692% +27.356%]
Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
1 (1.00%) high mild
1 (1.00%) high severe
fsb/zstd_parquet_2 time: [9.2977 ms 9.4085 ms 9.5422 ms]
thrpt: [1.6503 GiB/s 1.6737 GiB/s 1.6937 GiB/s]
change:
time: [−30.266% −29.333% −28.383%] (p = 0.00 <
0.05)
thrpt: [+39.632% +41.508% +43.401%]
Performance has improved.
Found 7 outliers among 100 measurements (7.00%)
4 (4.00%) high mild
3 (3.00%) high severe
fsb/cdc time: [7.9524 ms 7.9700 ms 7.9878 ms]
thrpt: [1.9714 GiB/s 1.9758 GiB/s 1.9802 GiB/s]
change:
time: [−21.280% −20.793% −20.375%] (p = 0.00 <
0.05)
thrpt: [+25.589% +26.251% +27.033%]
Performance has improved.
Found 2 outliers among 100 measurements (2.00%)
2 (2.00%) high mildaa
```
</details>
# Are there any user-facing changes?
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If there are any breaking changes to public APIs, please call them out.
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No.
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