> ## Documentation Index
> Fetch the complete documentation index at: https://codspeed.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.
> Learn how to improve your benchmarking process performance
# Sharded Benchmarks
Running benchmarks can be quite long and slow down your CI process. With
CodSpeed, you can run multiple benchmark commands in the same CI workflow. When
running heavy benchmark suites, this can divide the total runtime by the number
of jobs, dramatically speeding up your CI pipeline.
We recommend limiting each shard to fewer than 1,000 benchmarks.
You can speed up your CI even further by combining sharded benchmarks with
[partial runs](/features/partial-runs). This way, you can run only the
benchmark suites that are relevant to the code changes in your pull request.
## How to split the execution of benchmark suites?
Sharding allows you to run your benchmarks in several commands, with each
command running a subset of your benchmarks.
There are two main ways of sharding your benchmarks:
* splitting them in several files, and running each file or folder independently
* using a sharding tool provided by your benchmarking framework
Check the sharding docs corresponding to your benchmarking framework:
* Python:
* [`pytest`](/benchmarks/python#running-benchmarks-in-parallel-ci-jobs)
* NodeJS:
* [`vitest`](/benchmarks/nodejs/vitest#running-benchmarks-in-parallel-ci-jobs)
* Rust:
* [`divan`](/benchmarks/rust/divan#running-benchmarks-in-parallel-ci-jobs)
* [`criterion`](/benchmarks/rust/criterion#running-benchmarks-in-parallel-ci-jobs)
* [`bencher`](/benchmarks/rust/bencher#running-benchmarks-in-parallel-ci-jobs)
## Configure your CI workflow to use sharded benchmarks
CodSpeed will only supports emitting results from your benchmarks if you split
them within a single CI workflow.
If you run benchmarks in multiple CI workflows, CodSpeed will not be able to
aggregate the results correctly, and you may see incomplete or missing data in
your CodSpeed reports.
When running benchmarks across multiple jobs, all jobs **must use the same
authentication method** (either all OIDC, all static tokens, or all tokenless).
Mixing authentication methods will prevent CodSpeed from aggregating the results
correctly.
Once you've sharded your benchmarks, you can run using several CI jobs within
the same workflow, depending on your CI provider:
* [GitHub Actions](/integrations/ci/github-actions#running-benchmarks-in-parallel-ci-jobs)
* [Gitlab CI](/integrations/ci/gitlab-ci#running-benchmarks-in-parallel-ci-jobs)
## Multiple languages benchmarks
With benchmarks written in several languages, it can be difficult to get a
unified performance overview of your project.
With CodSpeed, you can run benchmarks written in multiple languages. When run in
the same CI workflow, CodSpeed will aggregate the results of these benchmarks
into a single report.
For example, using `pytest` and `vitest`:
```yaml .github/workflows/codspeed.yml icon="github" theme={null}
jobs:
python-benchmarks:
name: "Run Python benchmarks"
runs-on: ubuntu-latest
permissions: # optional for public repositories
contents: read # required for actions/checkout
id-token: write # required for OIDC authentication with CodSpeed
steps:
- uses: actions/checkout@v5
- name: Install required-version defined in uv.toml
uses: astral-sh/setup-uv@v7
- uses: actions/setup-python@v6
with:
python-version: 3.12.8
- name: Run benchmarks
uses: CodSpeedHQ/action@v4
with:
mode: simulation
run: uv run pytest tests/benchmarks/ --codspeed
nodejs-benchmarks:
name: "Run NodeJS benchmarks"
runs-on: ubuntu-latest
permissions: # optional for public repositories
contents: read # required for actions/checkout
id-token: write # required for OIDC authentication with CodSpeed
steps:
- uses: actions/checkout@v5
- uses: "actions/setup-node@v6"
- name: Install dependencies
run: npm install
- name: Run benchmarks
uses: CodSpeedHQ/action@v4
with:
mode: simulation
run: npm exec vitest bench
```