v2.0.0-alpha.1

This is the first alpha release of hyperfine 2.0. Command-line options and export formats may change before the stable release. See the breaking changes below when migrating from hyperfine 1.x.

Features

• Add support for alternative performance metrics (peak memory usage, CPU cycles, instructions, cache misses, branch misses, ...). By default, hyperfine will now display wall-clock time and peak memory usage (wall-clock time only on Windows),
  but users can use the new --metrics option to select different performance metrics.
• The terminal output now shows an overview of all selected performance metrics, including relative changes.
• Python plotting and analysis scripts support the new JSON format and can select performance metrics with --metric, see #981 and #984 (@sharkdp).

Breaking changes

• Benchmarked commands are now executed directly by default, without an intermediate shell (--shell=none). Use -S (an alias for --shell=default) to restore the previous behavior (sh on Unix, cmd.exe on Windows), or select a shell with --shell <SHELL>.

• The JSON format for --export-json has changed (schema version 2). The new format now includes metadata, per-run measurements, and statistical summaries for all measured quantities, see #790 (@sharkdp). Code that reads those exported JSON files must be updated. For example, results[i].mean is now results[i].summary.time_wall_clock.mean, and results[i].times is replaced by results[i].measurements[j].time_wall_clock.value. The new structure looks like this:

  {
      "schema_version": 2,
      "primary_metric": "time_wall_clock",
      "metadata": {
          "hyperfine_version": "2.0.0-alpha.1",
          "start_time": "2026-10-06T12:00:00Z",
          "platform": {"os": "Linux", "architecture": "x86_64"}
      },
      "results": [
          {
              "command": "sleep 1",  # Actual command after parameter substitution
              "name": "wait 1s",  # Optional custom name, separate from the command
              "parameters": {"duration": {"value": "1"}},  # Values are now objects
              "measurements": [  # One entry per run, excluding warmups
                  {
                      "time_wall_clock": {"value": 1.0, "unit": "second"},
                      "time_user": {"value": 0.0, "unit": "second"},
                      "time_system": {"value": 0.0, "unit": "second"},
                      "memory_peak_resident": {"value": 1048576.0, "unit": "byte"},
                      "exit_code": 0
                  },
                  ...  # Further runs omitted
              ],
              "summary": {
                  "time_wall_clock": {
                      "unit": "second",
                      "count": 2,
                      "mean": 1.0,
                      "stddev": 0.0,
                      "median": 1.0,
                      "min": 1.0,
                      "max": 1.0
                  }
                  # Other metrics have the same summary structure.
              }
          }
      ]
  }

  Times are always exported in seconds and memory in bytes.

• --time-unit/-u has been removed. Units can now be selected using the --metrics METRIC[:UNIT],… option, e.g. --metrics time_wall_clock:ms,memory_peak_resident:MiB.

• --sort has been removed. It complicated hyperfine significantly and doesn't make too much sense with the new output format.

• --reference and --reference-name have been removed (for now). The first command is always considered as the reference command.

• The format of Markdown, AsciiDoc, org-mode and CSV exports has also been changed. These formats contain only the primary metric (the first metric selected by --metrics). CSV now includes columns with the name and the unit of the primary metric.