[core] Fix flaky recursive cancel test

python/ray/tests/test_cancel.py

@@ -458,29 +458,32 @@ def remote_wait(sg):
 
 @pytest.mark.parametrize("use_force", [True, False])
 def test_recursive_cancel(shutdown_only, use_force):
-    ray.init(num_cpus=4)
+    ray.init(num_cpus=2)
 
     @ray.remote(num_cpus=1)
-    def inner():
+    def inner(signal_actor):
+        signal_actor.send.remote()
         while True:
             time.sleep(0.1)
 
     @ray.remote(num_cpus=1)
-    def outer():
-        x = [inner.remote()]
-        print(x)
+    def outer(signal_actor):
+        _ = inner.remote(signal_actor)
         while True:
             time.sleep(0.1)
 
-    @ray.remote(num_cpus=4)
+    @ray.remote(num_cpus=2)
     def many_resources():
-        return 300
+        return True
 
-    outer_fut = outer.remote()
+    signal_actor = SignalActor.remote()
+    outer_fut = outer.remote(signal_actor)
+    # Wait until both inner and outer are running
+    ray.get(signal_actor.wait.remote())
     many_fut = many_resources.remote()
     with pytest.raises(GetTimeoutError):
         ray.get(many_fut, timeout=1)
-    ray.cancel(outer_fut)
+    ray.cancel(outer_fut, force=use_force)
     with pytest.raises(valid_exceptions(use_force)):
         ray.get(outer_fut, timeout=10)