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perf: release memory when guest leaves #22

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Merged
MeteorsLiu merged 1 commit into from
Sep 20, 2026
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perf: release memory when guest leaves #22

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3 changes: 3 additions & 0 deletions guest_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,9 @@ func guestEntry() {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
// runGuest has released its state graph and input mapping. Collect after
// those roots leave the stack, before the guest process exits.
runtime.GC()

@fennoai fennoai Bot Sep 20, 2026

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guestEntry replaces main.main, so once it returns the guest process exits and the OS reclaims the entire address space regardless of GC state. A synchronous runtime.GC() here does a full stop-the-world mark/sweep whose only product is freed heap that is about to be discarded anyway — it adds teardown latency on every Run without an observable benefit.

The deterministic cleanup this seems aimed at is already handled inside runGuest: defer unix.Close(3) and the deferred unmap() (munmap) run during runGuest's return, before control reaches this line. I confirmed there are no runtime.SetFinalizer registrations in the production state/reflectx packages, so GC won't trigger any observable finalizer cleanup either.

The comment is also slightly inaccurate: runGuest doesn't explicitly "release its state graph" — the graph is a stack local that simply becomes unreachable on return; only the input mapping is explicitly released (via unmap()).

Suggestion: remove the runtime.GC() call, or — if it's retained for a specific measured reason (e.g., heap-profile hygiene for tooling) — document that concrete reason and consider gating it so it doesn't run on the hot path.

}

func runGuest() (err error) {
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