GH-41159: [Go][Parquet] Improvement Parquet BitWriter WriteVlqInt Performance

[DuanWeiFan]

GH-41159

Rationale for this change

This change improves Parquet FileWriter performance while writing parquets from arrow Records.
We saw a speed improvement from writing 320k rows/sec -> 650 rows/sec after making this change.

What changes are included in this PR?

This PR reuses the buf variable being used by the bitWriter when writing parquet files.

Are these changes tested?

Yes

Are there any user-facing changes?

No

Authored-by: @hhoughgg

• GitHub Issue: [Go] [Parquet] Improvement Performance on Parquet BitWriter WriteVlqInt #41159

[github-actions]

⚠️ GitHub issue #41159 has been automatically assigned in GitHub to PR creator.

[zeroshade]

Thanks for this! It's a great find. Do you think you could add a benchmark into the test file to track this so that we can make sure we don't introduce any performance regressions in the future?

[DuanWeiFan]

thanks for checking @zeroshade
Yeah I just added the benchmark for the method to the pr.

And here's the Benchmark Test Before vs After code change

--- Before
goos: darwin
goarch: amd64
pkg: github.com/apache/arrow/go/v15/parquet/internal/utils
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkBitWriter
BenchmarkBitWriter-12    	40391650	        28.91 ns/op	      17 B/op	       1 allocs/op
PASS
ok  	github.com/apache/arrow/go/v15/parquet/internal/utils	3.107s

--- After
goos: darwin
goarch: amd64
pkg: github.com/apache/arrow/go/v15/parquet/internal/utils
cpu: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
BenchmarkBitWriter
BenchmarkBitWriter-12    	107185990	         9.702 ns/op	       1 B/op	       0 allocs/op
PASS
ok  	github.com/apache/arrow/go/v15/parquet/internal/utils	3.111s

[zeroshade]

Fantastic, thanks! I'll merge once CI completes

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 5 benchmarking runs that have been run so far on merge-commit ec2d7cb.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 1 possible false positive for unstable benchmarks that are known to sometimes produce them.