fix(avr8js): resolve native Node before emulation by zackees · Pull Request #1697 · FastLED/fbuild

zackees · 2026-10-22T05:34:53Z

Fixes #1694. Coordinated with FastLED/FastLED#4884 and FastLED/FastLED#4895.

When node comes from nodejs-wheel, it is a Python launcher with native Node as a child. AVR8JS previously monitored the launcher; stopping it left Node holding the output pipes open, so test-emu hung after success/error markers or timeouts.

Discover Node's native executable with node --print process.execPath, validate the absolute path, and use that executable for headless emulation. Both production headless AVR8JS entry points share this discovery. The runner now owns native Node directly.

Validation:

The native-executable discovery regression failed before the fix and passed afterwards.
Real-Node integration tests passed under FastLED's nodejs-wheel uv run environment, covering executable identity plus success, error, and timeout shutdown. They are explicitly marked as requiring Node.js and do not require npm downloads or firmware.
FastLED's Uno Test firmware returned automatically after both serial markers through the fixed native binaries.
A second Uno run returned the expected timeout failure automatically.
Daemon clippy with warnings denied and workspace formatting passed. The source-bound local Linux and Dylint gates passed for the complete 2.5.43 candidate (882 seconds total).

Release preparation:

Bump workspace, Python package, and lockfile versions together to 2.5.43.
Refresh the generated platform-boundary inventory: the new tests shift one Windows cfg line from 146 to 224. Linux and Windows inventory checks, boundary ledger validation, Rust pin consistency, and all 37 scanner/policy tests pass locally.
After merge, run the explicit exact-SHA release dry run, then publish that same candidate and update FastLED’s dependency pin.

Release complete: 2.5.43, with all five PyPI wheels verified. Both the exact-SHA dry run and publication run passed for c621e34b0db292d44dc9a400d3b678399d8b37ff. FastLED/FastLED#4895 updates the consumer pin and restores native local/CI emulation. The installed published wheel passed FastLED Test and Blink in 35.48 seconds with no development overrides.

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crates/fbuild-daemon/src/handlers/emulator/avr8js_npm.rs
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📝 Walkthrough

find_node now returns the absolute executable path reported by Node’s process.execPath. Added ignored integration tests check executable identity and verify that headless runs finish with success, error, and timeout outcomes.

Changes: AVR8JS Node executable discovery

Layer / File(s)	Summary
Native Node resolution and integration coverage `crates/fbuild-daemon/src/handlers/emulator/avr8js_npm.rs`, `crates/fbuild-daemon/src/handlers/emulator/tests_npm_cache.rs`	`find_node` probes `process.execPath` and returns the reported absolute path. Ignored integration tests check executable identity and headless-runner success, error, and timeout outcomes.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 0d716

Headless emulation now launches native Node rather than the Python launcher that could leave it waiting on open output pipes. No actionable merge-blocking risk remains from this change.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 71.43% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 14 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: resolving the native Node executable before AVR8JS emulation.
Linked Issues check		Issue `#1694` requires direct ownership of native Node during headless AVR8JS runs. `find_node` now runs `node --print process.execPath`, trims the result, and rejects non-absolute paths. The shared dis…
Out of Scope Changes check		The changes are limited to native Node discovery and regression tests for the launcher shutdown failure. The tests directly verify the executable identity and the required completion outcomes. No unre…

Full details: Linked Issues check

Explanation

Issue #1694 requires direct ownership of native Node during headless AVR8JS runs. find_node now runs node --print process.execPath, trims the result, and rejects non-absolute paths. The shared discovery is used by both production headless entry points. The added Node.js integration tests cover executable identity and success-marker, error-marker, and timeout shutdown. The PR also reports successful FastLED Uno success and timeout runs.

Full details: Out of Scope Changes check

Explanation

The changes are limited to native Node discovery and regression tests for the launcher shutdown failure. The tests directly verify the executable identity and the required completion outcomes. No unrelated change is established.

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Inline comments:
Review comments at
@crates/fbuild-daemon/src/handlers/emulator/avr8js_headless.rs:
- Line 124: Update the process monitoring flow around child.wait() and
kill_tokio_tree so the timeout path can still terminate descendants after the
launcher exits; retain a valid termination handle before reaping the launcher,
or terminate the process tree before reaping it.

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crates/fbuild-core/src/platform/process.rs
crates/fbuild-daemon/src/handlers/emulator/avr8js_headless.rs
crates/fbuild-daemon/src/handlers/emulator/tests_process.rs

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zackees · 2026-10-22T07:16:03Z

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fix(avr8js): stop launcher descendants before draining output

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fastled-project-sync Bot added this to FastLED Tracker Oct 22, 2026

zackees added the ci-test Run extended CI tests beyond the routine minimal gate label Oct 22, 2026

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Comment thread crates/fbuild-daemon/src/handlers/emulator/avr8js_headless.rs Outdated

zackees added 2 commits October 21, 2026 23:24

fix(avr8js): resolve the native Node executable before emulation

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zackees changed the title ~~fix(avr8js): stop launcher descendants before draining output~~ fix(avr8js): resolve native Node before emulation Oct 22, 2026

zackees mentioned this pull request Oct 22, 2026

fix(avr8js): test-emu hangs after stopping the nodejs-wheel launcher #1694

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chore: bump version to 2.5.43

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zackees merged commit c621e34 into main Oct 22, 2026
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fix(avr): allow Servo to own Timer1 vector FastLED/FastLED#4884

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fix(avr8js): use native fbuild 2.5.43 for emulation FastLED/FastLED#4895

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fix(avr8js): resolve native Node before emulation - #1697

fix(avr8js): resolve native Node before emulation#1697
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