Microbench

Running the same script on a laptop, cloud VM, or cluster can produce different results. Maybe some nodes have different GPUs, or you're running a different git commit without realising it.

Microbench records the context alongside your timings: Python version, package versions, hostname, hardware, environment variables, git commit, and more. When performance varies across machines or runs, the metadata tells you why. When you need to reproduce a result, it shows exactly what was running.

Unlike other benchmarking tools, Microbench focuses on reproducibility metadata — capturing these details is cheap and routine, so you can do it for every run, not just when something goes wrong.

Two ways to use it

Microbench has two modes:

• CLI — wraps any command (Python or not) with a single line; no code changes required. Ideal for SLURM jobs and shell scripts.
• Python API — decorates functions or wraps code blocks for richer capture: sub-timings, return values, live package versions, async support.

Results are saved to a JSONL file, Redis, or an HTTP endpoint. File writes use O_APPEND and are safe for concurrent writes from multiple processes.

See CLI vs Python API below to help decide which to use.

What metadata can be captured?

Metadata are captured through mixins — small, composable modules that can be enabled from the CLI or mixed into a Python class. A sensible default set is active out of the box.

Metadata	CLI flag	Python mixin
Run ID, version, timezone, duration(s), start/finish times, invocation method	(default)	(default)
Python version, prefix, and executable	(default)	(default: included in MicroBench)
Hostname, OS; CPU core count and total RAM (requires psutil)	(default)	MBHostInfo
All SLURM_* environment variables	(default)	MBSlurmInfo
Loaded Environment Modules / Lmod stack	(default)	MBLoadedModules
Current working directory	(default)	MBWorkingDir
Git repo, commit hash, branch, dirty flag	--mixin git-info	MBGitInfo
SHA-256 (or other) hash of specified files	--mixin file-hash	MBFileHash
Installed Python packages and versions	--mixin installed-packages	MBInstalledPackages
Installed Conda packages and versions	--mixin conda-packages	MBCondaPackages
NVIDIA GPU names, memory, and attributes	--mixin nvidia-smi	MBNvidiaSmi
Cgroup CPU/RAM limits (containers, Linux only)	--mixin cgroup-limits	MBCgroupLimits
Function call arguments	—	MBFunctionCall
Function return value	—	MBReturnValue
Peak memory over a function call via tracemalloc	—	MBPeakMemory
Python packages loaded into the caller's globals	—	MBGlobalPackages
Line-by-line performance profile	—	MBLineProfiler

Installation

Requires Python 3.10+. No mandatory dependencies outside the standard library.

pip install microbench

Quick start — CLI

Wrap any command and capture host metadata alongside timing, with no code changes required:

microbench --outfile results.jsonl -- ./run_simulation.sh --steps 1000

This records one JSONL record per invocation. By default it captures timing, hostname, Python version, SLURM variables, loaded modules, and working directory. Add --monitor-interval to sample CPU and RSS memory over time:

microbench --outfile results.jsonl --monitor-interval 30 -- python train_model.py

Tag runs with custom fields:

microbench --outfile results.jsonl --field experiment=run-42 -- ./run.sh

Run microbench --help or microbench --show-mixins to see all options.

Example output

microbench -- echo "hello"

Output (written to stdout when --outfile is omitted):

{
  "mb": {
    "run_id": "8a3d213a-d7c2-44cb-a42f-1b68e6e0180e",
    "version": "2.0.0",
    "timezone": "UTC",
    "duration_counter": "perf_counter"
  },
  "call": {
    "invocation": "CLI",
    "name": "echo",
    "working_dir": "/home/user",
    "command": ["echo", "hello"],
    "durations": [0.004],
    "start_time": "2026-03-17T14:36:08.140607+00:00",
    "finish_time": "2026-03-17T14:36:08.144707+00:00",
    "returncode": [0]
  },
  "host": {
    "hostname": "cluster-node-04",
    "os": "linux",
    "cpu_cores_logical": 32,
    "cpu_cores_physical": 16,
    "ram_total": 137438953472
  },
  "python": {
    "version": "3.13.1",
    "prefix": "/opt/conda/envs/myenv",
    "executable": "/opt/conda/envs/myenv/bin/python3.13"
  },
  "slurm": {},
  "loaded_modules": {}
}

The CLI supports additional options, including capturing stdout/stderr, setting timeouts, and repeat iterations for benchmarking. See the CLI documentation for the full option reference.

Quick start — Python API

For Python-specific use cases, decorate functions directly:

from microbench import MicroBench

bench = MicroBench(outfile='/home/user/results.jsonl', experiment='baseline')

@bench
def my_function(n):
    return sum(range(n))

my_function(1_000_000)

results = bench.get_results()              # list of dicts — no extra dependencies
results = bench.get_results(format='df')  # pandas DataFrame
bench.summary()                           # quick stats printout

Each call produces one record. With get_results(flat=True) the record looks like:

   mb.run_id                             mb.version  call.name   call.durations  experiment
0  3f2a1b4c-8d9e-4f2a-b1c3-d4e5f6a7b8c9  2.0.0      my_function  [0.049823]     baseline

CLI vs Python API

Use case	Recommended
Shell scripts, compiled executables, or non-Python programs	CLI
SLURM jobs or batch scripts	CLI
One-off timing with host metadata, no code changes	CLI
Python functions needing sub-timings (bench.time()), return-value capture, or line-by-line profiling	Python API
Custom capture logic (subclassing mixins)	Python API
Capturing live Python module versions (not just what's installed)	Python API
Async Python functions	Python API

Python API — extended example

from microbench import MicroBench, MBFunctionCall, MBHostInfo, MBSlurmInfo
import numpy, pandas, time

class MyBench(MicroBench, MBFunctionCall, MBHostInfo, MBSlurmInfo):
    outfile = '/home/user/my-benchmarks.jsonl'
    capture_versions = (numpy, pandas)   # record live module versions
    env_vars = ('CUDA_VISIBLE_DEVICES',) # capture env vars as env.<NAME>

benchmark = MyBench(experiment='run-1', iterations=3,
                    duration_counter=time.monotonic)

@benchmark
def myfunction(arg1, arg2):
    ...

myfunction(x, y)

Mixins added here:

• MBFunctionCall records the arguments arg1 and arg2.
• MBHostInfo captures host.hostname, host.os, CPU cores, and RAM.
• MBSlurmInfo captures all SLURM_* environment variables.

MBPythonInfo is included in MicroBench by default — no need to list it explicitly.

See the full documentation for context managers, async support, sub-timings, output sinks, and more.

Documentation

Full documentation, including a getting-started guide, mixin reference, and API reference, is at https://alubbock.github.io/microbench/.

Citing microbench

If you use microbench in your research, please cite:

Lubbock, A.L.R. and Lopez, C.F. (2022). Microbench: automated metadata management for systems biology benchmarking and reproducibility in Python. Bioinformatics, 38(20), 4823–4825. https://doi.org/10.1093/bioinformatics/btac580

Although the paper was written in the context of systems biology, microbench is a general-purpose benchmarking tool applicable to any Python workload.

Feedback

Bug reports and feature requests are welcome in GitHub issues.