Fail tasks exceeding no-workers-timeout (#8806)

Author: hendrikmakait

distributed/distributed-schema.yaml

@@ -81,16 +81,15 @@ properties:
             - string
             - "null"
             description: |
-              Shut down the scheduler after this duration if there are pending tasks,
-              but no workers that can process them. This can either mean that there are
-              no workers running at all, or that there are idle workers but they've been
-              excluded through worker or resource restrictions.
+              Timeout for tasks in an unrunnable state.
+
+              If task remains unrunnable for longer than this, it fails. A task is considered unrunnable IFF
+              it has no pending dependencies, and the task has restrictions that are not satisfied by 
+              any available worker or no workers are running at all.
 
               In adaptive clusters, this timeout must be set to be safely higher than
               the time it takes for workers to spin up.
 
-              Works in conjunction with idle-timeout.
-
           work-stealing:
             type: boolean
             description: |

distributed/distributed.yaml

@@ -19,7 +19,7 @@ distributed:
     # after they have been removed from the scheduler
     events-cleanup-delay: 1h
     idle-timeout: null       # Shut down after this duration, like "1h" or "30 minutes"
-    no-workers-timeout: null # Shut down if there are tasks but no workers to process them
+    no-workers-timeout: null # If a task remains unrunnable for longer than this, it fails.
     work-stealing: True     # workers should steal tasks from each other
     work-stealing-interval: 100ms  # Callback time for work stealing
     worker-saturation: 1.1  # Send this fraction of nthreads root tasks to workers