(Issue)- unbounded memory growth during actors cycling.
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- Dominant language
- Rust
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Description
Summary:-
ActorContextShared::reset_runtime_state() in rivetkit-napi uses std::mem::forget to avoid a panic when dropping a napi::Ref on a Tokio worker thread (where no Node.js Env is available). This leaks one JS object reference slot per actor wake cycle. Over time in long-running processes with many actors cycling through sleep/wake, this is unbounded memory growth.
Problem:-
When an actor wakes from sleep, reset_runtime_state() is called to clear the previous JS state object. The napi::Ref type requires calling .unref(env) with a valid Node.js Env handle to properly release the reference. But reset_runtime_state() runs on a Tokio worker thread where no Env exists.
The current code uses std::mem::forget(old) to suppress the destructor. This avoids a debug_assert panic in napi-rs, but permanently leaks the underlying V8 reference slot.
The same pattern appears in the Drop impl for ActorContextShared.
File: rivetkit-typescript/packages/rivetkit-napi/src/actor_context.rs
if let Some(old) = self.runtime_state.lock().take() {
std::mem::forget(old);
}
Impact:-
- Rivet Actors are designed to sleep and wake frequently. An actor that wakes 100 times leaks 100 JS reference slots.
- The leak is per-actor, per-wake. A deployment with thousands of actors cycling through sleep/wake accumulates leaked references without bound.
- The only relief is process restart.
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start in rivetkit-typescript/packages/rivetkit-napi/src/actor_context.rs, reading ActorContextShared::reset_runtime_state() and its Drop implementation together. Trace how napi::Ref is released when a valid Node.js Env is available and how actor wake cycles reach these paths. Done means repeated sleep/wake cycles release JS references without panic or unbounded growth.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- node.js, rust
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 55/100