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Rubén Norte
0f9b8e4a62
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
41 lines
1.2 KiB
Bash
Executable File
41 lines
1.2 KiB
Bash
Executable File
#!/bin/bash
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# Copyright (c) Meta Platforms, Inc. and affiliates.
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#
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# This source code is licensed under the MIT license found in the
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# LICENSE file in the root directory of this source tree.
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set -e
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if [[ -f "BUCK" && -z "$FANTOM_FORCE_OSS_BUILD" ]]; then
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export JS_DIR='..'
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else
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if [[ ! -f "private/react-native-fantom/build/tester/fantom_tester" ]]; then
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yarn workspace @react-native/fantom build
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fi
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export FANTOM_FORCE_OSS_BUILD=1
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fi
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# The Fantom Jest process hosts a single shared Metro server. Each test
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# triggers a fresh Metro bundle build whose dependency graph (transformed
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# modules, source maps, inverse-deps, file-watcher subscription) lives in
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# memory until the per-test DELETE evicts it. With the maxWorkers cap in
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# jest.config.js (~16 in-flight bundles at peak), 16 GB gives ~40% heap
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# headroom over the observed steady state of ~6 GB.
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export NODE_OPTIONS='--max-old-space-size=16384'
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# Parse arguments to extract custom flags
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ARGS=()
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for arg in "$@"; do
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case "$arg" in
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--benchmarks) export FANTOM_RUN_BENCHMARKS=1 ;;
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*) ARGS+=("$arg") ;;
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esac
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done
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if [[ -n "$FANTOM_RUN_BENCHMARKS" ]]; then
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ARGS+=("--runInBand")
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fi
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yarn jest --config private/react-native-fantom/config/jest.config.js "${ARGS[@]}"
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