Interpreter memory pressure can OOM in tight recursive loops before GC reclaims

[frostney]

Problem

Plain interpreted tight recursion can still hit --max-memory before the runtime reclaims unreachable values. PR #497 now narrows its scope to making manual Goccia.gc() safe during active interpreter/bytecode execution, but it does not solve this original memory-pressure case.

Reproduction

printf 'const fib = (n) => n < 2 ? n : fib(n - 1) + fib(n - 2);\nfib(24);\n' | ./build/GocciaScriptLoader --max-memory=500000 --output=json --asi

Current result

On t3code/gc-loop-reclaim at b8b8d9b6, after rebuilding the loader, this exits with RangeError:

Allocation failed: GC heap size exceeds the configured memory limit

Observed GC data from the JSON envelope:

liveBytes: 500128
limitBytes: 500000
collections: 0
collectedObjects: 0
endObjectCount: 9718

Expected behavior

The interpreter should have a safe way to reclaim unreachable temporaries/completed frames in tight function loops before throwing for memory pressure. The script should either complete under this limit or run a safe collection before deciding the heap is genuinely still over MaxBytes.

Findings from PR #497 investigation

• Broad escaped-reference publication and small-int pinning made the PR too large and regressed full TestRunner runtime from roughly 2s to 10s+.
• Narrowing Make Goccia.gc safe during active execution #497 restored TestRunner performance while preserving safe manual GC from active interpreter/bytecode execution.
• Immediate non-escaped call-scope freeing alone is not enough for Fibonacci; transient numeric values still accumulate.
• Trying to collect directly from TGocciaValue.AfterConstruction when MaxBytes is exceeded is unsafe with the current interpreter, because expression temporaries are not comprehensively rooted.
• A safer fix likely needs an interpreter safe-point / temporary-root model so memory-pressure collection can run only when current expression temporaries, call frames, return values, and host temps are visible to the marker.

Related

• Follow-up from Make Goccia.gc safe during active execution #497.