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b9cd44892c
### What? Adds `TurboMalloc::thread_park()` — a new method on `TurboMalloc` that calls `libmimalloc_sys::mi_collect(false)` to process mimalloc's lazy free lists when a Tokio worker thread parks. Registers it as an `on_thread_park` callback in every Tokio runtime that already registers `on_thread_stop`: - `turbopack-cli/src/main.rs` - `turbopack-cli/benches/small_apps.rs` - `next-napi-bindings/src/lib.rs` - `next-build-test/src/main.rs` - `turbo-tasks-backend/fuzz/src/graph.rs` ### Why? mimalloc uses deferred freeing: memory freed by one thread is not reclaimed immediately but is queued until that thread performs N more allocations. Tokio worker threads that are parked (waiting for work) don't allocate, so deferred frees accumulate indefinitely — memory is never returned to the OS until the thread wakes up and does real work. Calling `mi_collect(false)` on park processes the lazy free lists, allowing mimalloc to reclaim that memory, while avoiding the syscalls and globally synchronized operations that `mi_collect(true)` would trigger. ### How? - `thread_park()` only calls `mi_collect(false)` — it intentionally does **not** call `flush()`. `flush()` transfers the thread-local allocation counter to the global atomic and resets it to zero, which would violate the trace server's assumption that per-thread counters are monotonically increasing. Counter sync remains exclusively in `thread_stop()`. - `thread_park()` is feature-gated behind `cfg(all(feature = "custom_allocator", not(target_family = "wasm")))` and is a no-op otherwise. - `libmimalloc-sys` is added as a direct optional dependency under `[target.'cfg(not(target_family = "wasm"))'.dependencies]` (it was already a transitive dep via `mimalloc`) to access `mi_collect` directly, since `mimalloc`'s `use ffi::*` is not a public re-export. - In each `on_thread_park` callback, `TurboMalloc::thread_park()` is called **after** the existing SWC atom store GC, so atoms freed by that GC pass are also eligible for reclamation in the same collection. <!-- NEXT_JS_LLM_PR --> --------- Co-authored-by: Tobias Koppers <[email protected]> Co-authored-by: Claude <[email protected]>
35 lines
853 B
TOML
35 lines
853 B
TOML
[package]
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name = "turbo-tasks-malloc"
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version = "0.1.0"
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description = "A wrapper around mimalloc or the system allocator that tracks allocations"
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license = "MIT"
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edition = "2024"
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autobenches = false
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[lib]
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bench = false
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[dependencies]
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[target.'cfg(not(target_family = "wasm"))'.dependencies]
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libmimalloc-sys = { version = "0.1.44", features = [
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"extended",
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], optional = true }
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[target.'cfg(not(any(target_os = "linux", target_family = "wasm")))'.dependencies]
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mimalloc = { version = "0.1.48", features = [
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"v3",
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"extended",
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], optional = true }
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[target.'cfg(all(target_os = "linux", not(target_family = "wasm")))'.dependencies]
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mimalloc = { version = "0.1.48", features = [
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"v3",
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"extended",
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"local_dynamic_tls",
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], optional = true }
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[features]
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custom_allocator = ["dep:mimalloc", "dep:libmimalloc-sys"]
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default = ["custom_allocator"]
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