Build/Test Tools: Stop builds hanging on Node.js 24 shutdown

[manzoorwanijk]

Runs Grunt with V8's concurrent Maglev and Sparkplug compilers disabled, so builds stop hanging after Done..

Grunt ends a successful run with process.exit(0) (grunt.js:163). Node's exit handler joins the V8 platform worker pool, and when a background compile job is parked in CollectionBarrier::AwaitCollectionBackground waiting for a garbage collection the main thread can no longer run, the two deadlock:

main thread   node::Environment::Exit -> DisposePlatform -> NodePlatform::Shutdown
              -> WorkerThreadsTaskRunner::Shutdown -> uv_thread_join      [blocked]

V8Worker x2   MaglevConcurrentDispatcher::JobTask::Run -> MaglevCompiler::Compile
              -> HeapAllocator::AllocateRawWithRetryOrFailSlowPath
              -> CollectionBarrier::AwaitCollectionBackground             [blocked]

Node 24 turns on both --maglev and --concurrent-sparkplug, where Node 22 had neither, which is why this started with r63539. --concurrent-recompilation was already on under Node 22 and costs 2.2x build time to disable, so it is left alone. Upstream: nodejs/node#64274.

NODE_OPTIONS rejects V8 options, so tools/grunt.js carries them instead and every Grunt entry point routes through it. That includes the grunt script CI calls and the nested child in utils.js:234.

Previous attempts to contain this by timeout: #13564, r63643, r63647.

Testing instructions

1. Run npm run build:dev and confirm the process exits rather than stalling after Done..
2. Run npm run grunt jshint and confirm the exit code still propagates.

On macOS arm64 with Node 24.21.0 the stall appeared in 3 of 60 unpatched runs, always with the stack above, caught by running sample(1) on a process still alive after Done..

Trac ticket: https://core.trac.wordpress.org/ticket/66116

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code, Codex
Model(s): Claude Opus 5, GPT-5.3 Codex
Used for: Diagnosis, the native stacks, and drafting and reviewing the launcher. I verified the stacks, measurements and final change myself.

[github-actions]

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[github-actions]

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