fix(process): allow unref'd child processes to outlive parent#32563
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bartlomieju merged 3 commits intomainfrom Mar 17, 2026
Merged
fix(process): allow unref'd child processes to outlive parent#32563bartlomieju merged 3 commits intomainfrom
bartlomieju merged 3 commits intomainfrom
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Previously, calling `unref()` on a child process spawned via `node:child_process` or `Deno.ChildProcess` would still kill the child when the parent exited. This happened because tokio's `kill_on_drop(true)` was set at spawn time with no way to disable it later. This commit replaces tokio/deno_subprocess_windows's `kill_on_drop` with a custom `Drop` implementation on `ChildResource` that kills the child by PID only when a `kill_on_drop` flag is true. New ops `op_spawn_child_ref` and `op_spawn_child_unref` toggle this flag, and are called from `ChildProcess.ref()` and `ChildProcess.unref()` in JS. Closes #21446 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
kajukitli
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Mar 7, 2026
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lgtm — good fix for Node.js unref() semantics
the approach is correct:
- custom
Dropimpl onChildResourceinstead of tokio'skill_on_drop(true) kill_on_drop: Cell<bool>toggled byop_spawn_child_ref/unref- sends SIGKILL on drop only if
kill_on_dropis true
test coverage is solid — spawns child, calls unref, parent exits, verifies child wrote marker file
On Windows, non-detached children are assigned to a global job object with JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE, so they are always terminated when the parent exits — regardless of unref(). This is a Windows OS-level behaviour that cannot be changed after spawn. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The `multi_test` schema does not support `if` at the top level — it must be inside the individual test definition (`single_or_multi_step_test`). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
child_process.unref()killing the child process when the parent exits, instead of letting it continue running independently (Node.js behavior)kill_on_drop(true)with a customDroponChildResourcethat respects a togglablekill_on_dropflagop_spawn_child_ref/op_spawn_child_unrefops to control the flag from JSref()/unref()child_processpolyfill delegates toDeno.ChildProcess, so it gets the fix automaticallyTest plan
child_process_unref_survives— parent spawns child, callsunref(), exits; verifies child wrote a marker filechild_processspec tests pass (18/18)cargo check, format, and lint passCloses #21446
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