fix(ext/node): process.exit() in worker immediately halts execution#32169
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bartlomieju merged 4 commits intodenoland:mainfrom Feb 15, 2026
Merged
fix(ext/node): process.exit() in worker immediately halts execution#32169bartlomieju merged 4 commits intodenoland:mainfrom
bartlomieju merged 4 commits intodenoland:mainfrom
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In Node.js, process.exit() inside a worker immediately stops all JS execution at the C++ level. In Deno, it called workerClose() which triggered V8's terminate_execution(), but JS continued running because V8 only checks the termination flag at function entries and loop back-edges, not during function returns. Fix by adding an infinite loop after process.reallyExit() that gives V8 a loop back-edge to detect the pending termination and throw an uncatchable TerminationException. On the main thread the loop is unreachable since reallyExit() calls std::process::exit(). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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The fix seems a bit bizarre, but does work |
littledivy
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Feb 15, 2026
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| // In a worker, reallyExit() returns because Deno.exit() calls workerClose() | ||
| // instead of std::process::exit(). But workerClose() already called V8's | ||
| // terminate_execution(). Spinning here gives V8 a loop back-edge to detect | ||
| // the pending termination and throw an uncatchable TerminationException, | ||
| // matching Node.js behavior where process.exit() immediately halts all JS. | ||
| // On the main thread reallyExit() normally never returns, but users can | ||
| // override it (test-process-really-exit.js), so only spin in workers. | ||
| if (internals.__isWorkerThread) { | ||
| // deno-lint-ignore no-empty | ||
| for (;;) {} | ||
| } |
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I assume there is a stack guard in V8 for this so just a function call should be enough to trigger this
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I tried that with Claude I got this:
The tests fail — nop() alone isn't sufficient. The issue is that in Deno, process.reallyExit is a JS function (not a C++ binding like in Node.js), so V8's
stack guard spoofing from terminate_execution() may not persist through the multiple JS return frames between the op and the nop() call. The for (;;) {}
loop is needed because it provides a loop back-edge where V8 reliably checks for termination.
littledivy
approved these changes
Feb 15, 2026
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Summary
In Node.js,
process.exit()inside a worker immediately stops all JS execution at the C++ level. In Deno, it calledworkerClose()which triggered V8'sterminate_execution(), but JS continued running because V8 only checks the termination flag at function entries and loop back-edges — not during function returns.Adds an infinite loop after
process.reallyExit()that gives V8 a loop back-edge to detect the pending termination and throw an uncatchableTerminationException. On the main thread the loop is unreachable sincereallyExit()callsstd::process::exit().Enables 2 new node_compat tests:
test-worker-voluntarily-exit-followed-by-addition.jstest-worker-voluntarily-exit-followed-by-throw.jsTest plan
cargo test --test node_compat parallel -- --filter "test-worker-voluntarily-exit"— both passcargo test --test node_compat parallel -- --filter "test-worker-terminate"— no regressionscargo test --test node_compat parallel -- --filter "test-worker-exit"— no regressions🤖 Generated with Claude Code