Pool.trace()

Register a hook called as fn(event, id) at each task

Usage

Source

Pool.trace(fn)

lifecycle event this process observes: "submit" on the submitting thread; "start", "done", "error", "drop", "rehome" on worker handles. id is "<submitter slot>:<counter>", stable across processes. Registration is per-handle and per-process; None removes the hook. A hook exception is written as unraisable, never propagated into the pool.