Bug: dashboard would not show no-worker tasks

distributed/dashboard/components/scheduler.py

@@ -3343,7 +3343,7 @@ def update(self):
 
         for tp in self.scheduler.task_prefixes.values():
             states = tp.states
-            if any(states.get(s) for s in state.keys()):
+            if any(v for k, v in states.items() if k != "forgotten"):
                 state["memory"][tp.name] = states["memory"]
                 state["erred"][tp.name] = states["erred"]
                 state["released"][tp.name] = states["released"]

distributed/dashboard/tests/test_scheduler_bokeh.py

@@ -287,6 +287,30 @@ async def test_TaskProgress_empty(c, s, a, b):
     assert not any(len(v) for v in tp.source.data.values())
 
 
+@gen_cluster(client=True)
+async def test_TaskProgress_no_worker(c, s, a, b):
+    """The no-worker state has special treatment as dashes cause issues in Bokeh"""
+    tp = TaskProgress(s)
+
+    future = c.submit(slowinc, 0, resources={"foo": 1})
+    while not s.tasks:
+        await asyncio.sleep(0.01)
+
+    tp.update()
+    assert tp.source.data["all"] == [1]
+    assert tp.source.data["no_worker"] == [1]
+    assert tp.source.data["name"] == ["slowinc"]
+
+    del future
+    while s.tasks:
+        await asyncio.sleep(0.01)
+
+    tp.update()
+    assert tp.source.data["all"] == []
+    assert tp.source.data["no_worker"] == []
+    assert tp.source.data["name"] == []
+
+
 @gen_cluster(client=True)
 async def test_CurrentLoad(c, s, a, b):
     cl = CurrentLoad(s)