778 B
Change the core message loop to handle task and actor-runtime cancel requests immediately instead of scheduling them as is done for rpc-task requests.
In order to obtain more reliable teardown mechanics for (complex) actor trees it's important that we specially treat cancel requests as having higher priority. Previously, it was possible that task cancel requests could actually also themselves be cancelled if a "actor-runtime" cancel request was received (can happen during messy multi actor crashes that propagate). Instead cancels now block the msg loop until serviced and a response is relayed back to the requester. This alsoa allowed for improved debugger support since we have determinism guarantees about which processes must wait before hard killing their children.