std::runtime

Status: experimental

Goroutine / scheduler introspection and tuning.

Items

Item	Signature	Description
collect_cycles	fn collect_cycles() -> ()	Requests collection of unreachable reference cycles; returns ().
cycle_collection_supported	fn cycle_collection_supported() -> bool	Reports whether this execution tier reclaims unreachable reference cycles.
is_main_thread	fn is_main_thread() -> bool	Whether the caller runs on the process main thread, the one main starts on. Libraries whose platform APIs belong to that thread, such as windowing on macOS, check it before calling them.
scheduler_stats_json	fn scheduler_stats_json() -> String	Returns a compact JSON snapshot of goroutine scheduler counters.
arena_push	fn arena_push() -> ()	Opens an arena region for bump allocation.
arena_pop	fn arena_pop() -> ()	Closes the innermost arena region, freeing its slabs.
set_panic_hook	fn set_panic_hook(hook: Fn(String) -> ()) -> ()	Installs a hook invoked with the message on panic.
at_exit	fn at_exit(hook: Fn() -> ()) -> ()	Runs a closure when the program ends: returning from main, process::exit, or an uncaught panic. Hooks run last registered first.
cohort_push	fn cohort_push(policy: i64, timeout_ms: i64, isolation: i64, on_error: i64, uncancellable: i64, drain_ms: i64) -> ()	Opens a cohort on the running goroutine. Written cohort { } in source; the block desugars to this plus cohort_join and a deferred cohort_pop.
cohort_join	fn cohort_join() -> Result<(), errors::Error>	Waits for every child of the running goroutine's cohort and answers Result<(), errors::Error>.
cohort_pop	fn cohort_pop() -> ()	Closes the running goroutine's cohort, cancelling and joining anything still running.
cohorts	fn cohorts() -> Vec<String>	One descriptor line per live cohort, oldest id first: id, parent, completion policy, error disposition, outstanding count, and the spawn indices still running. A cohort is enumerable so a program can say what it is waiting on without joining it.
root	fn root() -> String	The root cohort's descriptor line, in the shape cohorts() answers, or an empty String when no cohort is open. The root is the one cohort every program has - main runs inside it - and the one whose drain bounds process exit.
cohort_cancelled	fn cohort_cancelled() -> bool	Whether the running goroutine's cohort has been cancelled. A CPU-bound child polls this to cooperate at a point of its own choosing.
cohort_cancel	fn cohort_cancel() -> ()	Cancels the running goroutine's cohort, winding its siblings down without failing it.

Cycle collection

collect_cycles() is experimental. The compiled runtime collects thread-local RC graphs; values that have crossed a goroutine boundary are excluded because concurrent mutation cannot safely participate in its thread-local trial-deletion pass. Break such cycles with Weak<T>.

The bytecode VM uses Arc-backed values and currently treats this call as a no-op. Weak<T>::upgrade() remains valid for the supported VM heap values, but collection-driven weak invalidation is not a cross-tier guarantee yet.