Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56529
Fantom runs every test through a single shared Metro server (started in
`globalSetup`). Jest's default `maxWorkers` is `numCpus - 1`, so on a
high-core box (e.g. 176 CPUs) ~175 workers fire bundle requests at Metro
concurrently. Each in-flight request makes Metro materialize a full
dependency `Graph` (transformed modules, source maps, inverse-deps,
file-watcher subscription), which is hundreds of MB.
The per-test `DELETE` eviction added in D101652820 only releases that
memory after the bundle response completes, so the simultaneous in-flight
set still blows past the previous Node `--max-old-space-size=8192` ceiling
in `scripts/fantom.sh` — the Metro process aborts with
`FATAL ERROR: Ineffective mark-compacts near heap limit` after just a
handful of test suites.
Two coordinated changes that balance throughput and safety:
- `scripts/fantom.sh`: bump the Node heap from 8 GB to 16 GB so we have
headroom over the observed steady-state peak.
- `private/react-native-fantom/config/jest.config.js`: cap `maxWorkers`
at `min(numCpus - 1, 16)`. With 8 workers the heap peaked at ~3 GB
(~400 MB / worker), so 16 workers fits comfortably under a 16 GB cap
with ~40% headroom.
This is intentionally a balance rather than a hard worker cap — bumping
the heap alone would still leave 100+ in-flight graphs racing GC, and
capping workers alone leaves throughput on the table on big machines.
Changelog: [Internal]
Reviewed By: andrewdacenko
Differential Revision: D101791795
fbshipit-source-id: 035c7235c32303f7b7f1eb05698b2a5cba90edc9
Summary:
When `--benchmarks` is passed to `yarn fantom`, automatically append
`--runInBand` to the Jest arguments. This ensures benchmarks run
sequentially in the same process, avoiding parallel test execution that
would introduce noise in performance measurements.
Changelog: [Internal]
Reviewed By: lenaic
Differential Revision: D100796022
fbshipit-source-id: b78aa44d65ef8618eec6fb08680b5b455cf2470b
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/56418
Changelog: [internal]
D92150163 excluded benchmark tests by default when running `yarn fantom` without `--benchmarks`. This was incorrect because it means benchmarks could silently break without being caught.
This changes the behavior so:
1. By default (without `--benchmarks`), benchmarks run in test mode (single iteration for correctness only), ensuring they do not break.
2. With `--benchmarks`, benchmarks run in full benchmark mode (multiple iterations for performance measurement).
Also renames `FANTOM_FORCE_TEST_MODE` to `FANTOM_RUN_BENCHMARKS` and `forceTestModeForBenchmarks` to `runBenchmarks` to better reflect the intent (opt-in to full benchmarks rather than opt-in to test mode).
Reviewed By: sammy-SC
Differential Revision: D100464314
fbshipit-source-id: 822cc5a25f0cdddf035616fdddf8619d27ef436a
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/54729
Changelog: [Internal]
- Created new build-fantom-runner action to compile the Fantom runner binary
- Modified run-fantom-tests action to download and use pre-built binary
- Updated test-all.yml workflow to run build and test as separate jobs
- Removed build dependencies and ccache configuration from test job
Reviewed By: cortinico
Differential Revision: D88012198
fbshipit-source-id: cd1c91b18cccc3c62b9edbcbeb131e80551369f1
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55725
changelog: [internal]
By default, `yarn fantom` now excludes benchmark tests (`*-benchmark-itest.js` files) to speed up regular test runs.
Benchmark tests are typically slower and used for performance analysis rather than correctness testing. Excluding them by default improves the developer experience for everyday test runs.
To run benchmark tests, use the new `--benchmarks` flag:
```
yarn fantom --benchmarks
```
Reviewed By: andrewdacenko
Differential Revision: D92150163
fbshipit-source-id: 4c40ef1ba542c4856221373d8239ba603e8f6620
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/52777
Changelog: [internal]
This significantly speeds up test execution in Fantom (around 2x in OSS and 6x at Meta) by starting a Metro server before all tests runs and reusing it across all tests to build test bundles, instead of spinning up a new Metro instance every time we run each test.
The architecture change (also considering the previous change in buck prebuilds) looks like this:
{F1980689532}
This is how is impacts execution times (compared to the baseline):
* OSS
* Before: 62s {F1980564286}
* After: 30s (**2x faster**) {F1980564265}
Reviewed By: andrewdacenko
Differential Revision: D78741903
fbshipit-source-id: b209f88925e49cc2a2067e8df9b7fa9a29b4c8d2
Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/52222
Changelog: [Internal]
Introduce environment option to force usage of OSS fantom test runner.
If env is not set - check for BUCK file in tester which is checked in for FB but not for OSS.
Reviewed By: rubennorte
Differential Revision: D77160761
fbshipit-source-id: 1701ff140ff2be1bbeacfb4305e9f89089cacb42
Rubén Norte