Remove RescheduleMsg

distributed/scheduler.py

@@ -3031,7 +3031,6 @@ def __init__(
             "release-worker-data": self.release_worker_data,
             "add-keys": self.add_keys,
             "long-running": self.handle_long_running,
-            "reschedule": self.reschedule,
             "keep-alive": lambda *args, **kwargs: None,
             "log-event": self.log_worker_event,
             "worker-status-change": self.handle_worker_status_change,
@@ -6568,26 +6567,20 @@ async def get_story(self, keys_or_stimuli: Iterable[str]) -> list[tuple]:
 
     transition_story = story
 
-    def reschedule(
-        self, key: str, worker: str | None = None, *, stimulus_id: str
-    ) -> None:
+    def reschedule(self, key: str, *, stimulus_id: str) -> None:
         """Reschedule a task
 
         Things may have shifted and this task may now be better suited to run
-        elsewhere
+        elsewhere.
+
+        Note
+        ----
+        This handler is used by work stealing exclusively.
+        When a task raises the Reschedule exception, it causes a transition to released
+        which, as soon as it reaches the scheduler, causes the task to immediately
+        transition back to waiting.
         """
-        try:
-            ts = self.tasks[key]
-        except KeyError:
-            logger.warning(
-                f"Attempting to reschedule task {key}, which was not "
-                "found on the scheduler. Aborting reschedule."
-            )
-            return
-        if ts.state != "processing":
-            return
-        if worker and ts.processing_on.address != worker:
-            return
+        assert self.tasks[key].state == "processing"
         self.transitions({key: "released"}, stimulus_id)
 
     #####################

distributed/tests/test_scheduler.py

@@ -1514,33 +1514,29 @@ async def test_log_tasks_during_restart(c, s, a, b):
     assert "exit" in str(s.events)
 
 
-@gen_cluster(client=True, nthreads=[("127.0.0.1", 1)] * 2)
+@gen_cluster(
+    client=True,
+    nthreads=[("", 1)] * 2,
+    config={"distributed.scheduler.work-stealing": False},
+)
 async def test_reschedule(c, s, a, b):
-    await c.submit(slowinc, -1, delay=0.1)  # learn cost
-    x = c.map(slowinc, range(4), delay=0.1)
-
-    # add much more work onto worker a
-    futures = c.map(slowinc, range(10, 20), delay=0.1, workers=a.address)
-
-    while len(s.tasks) < len(x) + len(futures):
-        await asyncio.sleep(0.001)
-
-    for future in x:
-        s.reschedule(future.key, stimulus_id="test")
+    xs = c.map(slowinc, range(100), key="x", delay=0.1)
+    while not a.state.tasks:
+        await asyncio.sleep(0.01)
+    assert len(a.state.tasks) == 50
 
-    # Worker b gets more of the original tasks
-    await wait(x)
-    assert sum(future.key in b.data for future in x) >= 3
-    assert sum(future.key in a.data for future in x) <= 1
+    ys = c.map(slowinc, range(100), key="y", delay=0.1, workers=[a.address])
+    while len(a.state.tasks) != 150:
+        await asyncio.sleep(0.01)
 
+    assert len(b.state.tasks) == 50
 
-@gen_cluster(client=True, nthreads=[("127.0.0.1", 1)] * 2)
-async def test_reschedule_warns(c, s, a, b):
-    with captured_logger(logging.getLogger("distributed.scheduler")) as sched:
-        s.reschedule("__this-key-does-not-exist__", stimulus_id="test")
+    for x in xs:
+        if x.key in a.state.tasks and s.tasks[x.key].state == "processing":
+            s.reschedule(x.key, stimulus_id="test")
 
-    assert "not found on the scheduler" in sched.getvalue()
-    assert "Aborting reschedule" in sched.getvalue()
+    while len(b.state.tasks) <= 50:
+        await asyncio.sleep(0.01)
 
 
 @gen_cluster(client=True)
@@ -3343,12 +3339,11 @@ async def test_worker_heartbeat_after_cancel(c, s, *workers):
 
 @gen_cluster(client=True, nthreads=[("", 1)] * 2)
 async def test_set_restrictions(c, s, a, b):
-
-    f = c.submit(inc, 1, workers=[b.address])
+    f = c.submit(inc, 1, key="f", workers=[b.address])
     await f
     s.set_restrictions(worker={f.key: a.address})
     assert s.tasks[f.key].worker_restrictions == {a.address}
-    s.reschedule(f, stimulus_id="test")
+    await b.close()
     await f
 
 

distributed/tests/test_worker.py

@@ -81,6 +81,7 @@
     ExecuteFailureEvent,
     ExecuteSuccessEvent,
     RemoveReplicasEvent,
+    RescheduleEvent,
     SerializedTask,
     StealRequestEvent,
 )
@@ -1180,20 +1181,24 @@ def some_name():
     assert result.startswith("some_name")
 
 
+@pytest.mark.slow
+@pytest.mark.parametrize("long_running", [False, True])
 @gen_cluster(client=True, nthreads=[("127.0.0.1", 1)] * 2)
-async def test_reschedule(c, s, a, b):
+async def test_reschedule(c, s, a, b, long_running):
     await s.extensions["stealing"].stop()
     a_address = a.address
 
     def f(x):
+        if long_running:
+            distributed.secede()
         sleep(0.1)
         if get_worker().address == a_address:
             raise Reschedule()
 
-    futures = c.map(f, range(4))
-    futures2 = c.map(slowinc, range(10), delay=0.1, workers=a.address)
+    futures = c.map(f, range(4), key=["x1", "x2", "x3", "x4"])
+    futures2 = c.map(slowinc, range(10), delay=0.1, key="clog", workers=[a.address])
     await wait(futures)
-
+    assert any(isinstance(ev, RescheduleEvent) for ev in a.state.stimulus_log)
     assert all(f.key in b.data for f in futures)
 
 

distributed/tests/test_worker_state_machine.py

@@ -35,7 +35,6 @@
     RefreshWhoHasEvent,
     ReleaseWorkerDataMsg,
     RescheduleEvent,
-    RescheduleMsg,
     SerializedTask,
     StateMachineEvent,
     TaskState,
@@ -227,8 +226,8 @@ def test_sendmsg_to_dict():
 def test_merge_recs_instructions():
     x = TaskState("x")
     y = TaskState("y")
-    instr1 = RescheduleMsg(key="foo", stimulus_id="test")
-    instr2 = RescheduleMsg(key="bar", stimulus_id="test")
+    instr1 = ReleaseWorkerDataMsg(key="foo", stimulus_id="test")
+    instr2 = ReleaseWorkerDataMsg(key="bar", stimulus_id="test")
     assert merge_recs_instructions(
         ({x: "memory"}, [instr1]),
         ({y: "released"}, [instr2]),

distributed/worker_state_machine.py

@@ -425,13 +425,11 @@ class ReleaseWorkerDataMsg(SendMessageToScheduler):
     key: str
 
 
-# Not to be confused with RescheduleEvent below or the distributed.Reschedule Exception
+# FIXME temp hack - do not merge
 @dataclass
-class RescheduleMsg(SendMessageToScheduler):
-    op = "reschedule"
-
-    __slots__ = ("key",)
-    key: str
+class DummyMsg(SendMessageToScheduler):
+    op = "dummy"
+    __slots__ = ()
 
 
 @dataclass
@@ -770,7 +768,7 @@ class AlreadyCancelledEvent(StateMachineEvent):
     key: str
 
 
-# Not to be confused with RescheduleMsg above or the distributed.Reschedule Exception
+# Not to be confused with the distributed.Reschedule Exception
 @dataclass
 class RescheduleEvent(StateMachineEvent):
     __slots__ = ("key",)
@@ -1693,7 +1691,7 @@ def _transition_waiting_constrained(
     def _transition_long_running_rescheduled(
         self, ts: TaskState, *, stimulus_id: str
     ) -> RecsInstrs:
-        return {ts: "released"}, [RescheduleMsg(key=ts.key, stimulus_id=stimulus_id)]
+        return {ts: "released"}, [DummyMsg(stimulus_id=stimulus_id)]
 
     def _transition_executing_rescheduled(
         self, ts: TaskState, *, stimulus_id: str
@@ -1702,7 +1700,7 @@ def _transition_executing_rescheduled(
             self.available_resources[resource] += quantity
         self.executing.discard(ts)
 
-        return {ts: "released"}, [RescheduleMsg(key=ts.key, stimulus_id=stimulus_id)]
+        return {ts: "released"}, [DummyMsg(stimulus_id=stimulus_id)]
 
     def _transition_waiting_ready(
         self, ts: TaskState, *, stimulus_id: str