use sync.Pool to retrieve bytes.Buffers

[wazazaby]

goos: darwin
goarch: arm64
pkg: github.com/wazazaby/vimebu
                                                          │   std.txt   │               pool.txt               │
                                                          │   sec/op    │   sec/op     vs base                 │
BuilderTestCases/metric_with_labels-10                      86.20n ± 1%   67.20n ± 1%   -22.03% (p=0.000 n=10)
BuilderTestCases/metric_with_single_label-10                54.06n ± 1%   48.38n ± 3%   -10.52% (p=0.000 n=10)
BuilderTestCases/metric_without_label-10                    25.23n ± 2%   34.35n ± 1%   +36.15% (p=0.000 n=10)
BuilderTestCases/no_name-10                                 2.066n ± 3%   4.625n ± 1%  +123.89% (p=0.000 n=10)
BuilderTestCases/some_empty_labels_and_values-10            62.45n ± 1%   57.93n ± 0%    -7.23% (p=0.000 n=10)
BuilderTestCases/values_contain_double_quotes-10            581.2n ± 1%   472.9n ± 0%   -18.64% (p=0.000 n=10)
BuilderTestCases/values_with_and_without_double_quotes-10   604.2n ± 2%   506.5n ± 0%   -16.18% (p=0.000 n=10)
geomean                                                     65.77n        68.62n         +4.33%

                                                          │    std.txt    │               pool.txt               │
                                                          │     B/op      │    B/op     vs base                  │
BuilderTestCases/metric_with_labels-10                      168.00 ± 0%     64.00 ± 0%  -61.90% (p=0.000 n=10)
BuilderTestCases/metric_with_single_label-10                 72.00 ± 0%     32.00 ± 0%  -55.56% (p=0.000 n=10)
BuilderTestCases/metric_without_label-10                     32.00 ± 0%     32.00 ± 0%        ~ (p=1.000 n=10) ¹
BuilderTestCases/no_name-10                                  0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
BuilderTestCases/some_empty_labels_and_values-10             72.00 ± 0%     48.00 ± 0%  -33.33% (p=0.000 n=10)
BuilderTestCases/values_contain_double_quotes-10             504.0 ± 0%     112.0 ± 0%  -77.78% (p=0.000 n=10)
BuilderTestCases/values_with_and_without_double_quotes-10    504.0 ± 0%     160.0 ± 0%  -68.25% (p=0.000 n=10)
geomean                                                                 ²               -49.86%                ²
¹ all samples are equal
² summaries must be >0 to compute geomean

                                                          │   std.txt    │               pool.txt               │
                                                          │  allocs/op   │ allocs/op   vs base                  │
BuilderTestCases/metric_with_labels-10                      3.000 ± 0%     1.000 ± 0%  -66.67% (p=0.000 n=10)
BuilderTestCases/metric_with_single_label-10                2.000 ± 0%     1.000 ± 0%  -50.00% (p=0.000 n=10)
BuilderTestCases/metric_without_label-10                    1.000 ± 0%     1.000 ± 0%        ~ (p=1.000 n=10) ¹
BuilderTestCases/no_name-10                                 0.000 ± 0%     0.000 ± 0%        ~ (p=1.000 n=10) ¹
BuilderTestCases/some_empty_labels_and_values-10            2.000 ± 0%     1.000 ± 0%  -50.00% (p=0.000 n=10)
BuilderTestCases/values_contain_double_quotes-10            7.000 ± 0%     1.000 ± 0%  -85.71% (p=0.000 n=10)
BuilderTestCases/values_with_and_without_double_quotes-10   7.000 ± 0%     1.000 ± 0%  -85.71% (p=0.000 n=10)
geomean                                                                ²               -59.79%                ²
¹ all samples are equal
² summaries must be >0 to compute geomean