Does dropping a Tokio JoinHandle cancel the spawned task?

Dropping the handle detaches observation rather than providing a general cancellation guarantee. The spawned work may continue after the caller loses its result. Retain the handle when completion or failure matters. Use the runtime’s cancellation mechanism deliberately and await termination when the workflow needs evidence of shutdown. For blocking tasks, understand the separate limits on aborting already-running work. Design cleanup around owned resources and cancellation-safe transitions. Test handle drop, explicit abort and normal completion as different cases. A canceled local task does not undo a remote request already processed. Before restarting side-effecting work, reconcile authoritative state rather than assuming loss of the handle means the operation never happened.