How to Track Custom Benchmarks with Bencher

Bencher supports the most popular benchmarking harnesses out-of-the-box, and we are always open to suggestions for new adapters. However there can be situations where an off-the-shelf benchmarking harness doesn’t fit your needs, necessitating the creation of a custom benchmarking harness. Lucky for you, Bencher also supports using a custom benchmarking harness. The easiest way to integrate your custom benchmark harness with Bencher is to output Bencher Metric Format (BMF) JSON.

This is an example of BMF JSON:

{
  "benchmark_name": {
    "latency": {
      "value": 88.0,
      "lower_value": 87.42,
      "upper_value": 88.88
    }
  }
}

In this example, the key benchmark_name would be the name of a Benchmark. Benchmark names can be any non-empty string up to 1024 characters. The benchmark_name object can contain multiple Measure names, slugs, or UUIDs as keys. If the value specified is a name or slug and the Measure does not already exist, it will be created for you. However, if the value specified is a UUID then the Measure must already exist. In this example, latency is the slug for the built-in Latency Measure. Each Project by default has a Latency (ie latency) and Throughput (ie throughput) Measure, which are measured in nanosecond (ns) and operations / second (ops/s) respectively. The Measure object contains a Metric with up to three values: value, lower_value, and upper_value. The lower_value and upper_value values are optional.

In this example, the latency Measure object contains the following values:

• A value of 88.0
• A lower_value of 87.42
• An upper_value of 88.88

You can use the bencher mock CLI subcommand to generate mock BMF data. We will use it as a placeholder for your own custom benchmark runner. Using bencher run and the json adapter we can track our benchmarks with the following command:

bencher run --adapter json "bencher mock"

If your results were instead stored in a file named results.json, then you could use the --file option to specify the file path. This works both with a benchmark command and without one.

With a benchmark command:

bencher run --file results.json --adapter json "bencher mock > results.json"

Without a benchmark command:

bencher mock > results.json && bencher run --file results.json --adapter json

Multiple Measures

In Bencher Metric Format (BMF) JSON the Benchmark object can contain multiple Measure names, slugs, or UUIDs as keys. If the value specified is a name or slug and the Measure does not already exist, it will be created for you. However, if the value specified is a UUID then the Measure must already exist. Each Measure object must contain a Metric with up to three values: value, lower_value, and upper_value. The lower_value and upper_value values are optional.

This is an example of BMF JSON with multiple Measures:

{
  "benchmark_name": {
    "latency": {
      "value": 88.0,
      "lower_value": 87.42,
      "upper_value": 88.88
    },
    "throughput" {
      "value": 5.55,
      "lower_value": 3.14,
      "upper_value": 6.30
    }
  }
}

In this example, the latency Measure object contains the following values:

• A value of 88.0
• A lower_value of 87.42
• An upper_value of 88.88

And the throughput Measure object contains the following values:

• A value of 5.55
• A lower_value of 3.14
• An upper_value of 6.30

You can use the bencher mock CLI subcommand with the --measure option to generate mock BMF data with multiple Measures. We will use it as a placeholder for your own custom benchmark runner. Using bencher run and the json adapter we can track our benchmarks with multiple Measures with the following command:

bencher run --adapter json "bencher mock --measure latency --measure throughput"

🐰 Congrats! You have learned how to track custom benchmarks! 🎉

Keep Going: How to Track Benchmarks in CI ➡