Fix test_dying_worker_get (#5908)

python/ray/tests/test_component_failures.py

@@ -26,6 +26,7 @@ from ray.tests.utils import (run_string_as_driver_nonblocking,
 def test_dying_worker_get(ray_start_2_cpus):
     @ray.remote
     def sleep_forever():
+        ray.experimental.signal.send("ready")
         time.sleep(10**6)
 
     @ray.remote
@@ -33,7 +34,7 @@ def test_dying_worker_get(ray_start_2_cpus):
         return os.getpid()
 
     x_id = sleep_forever.remote()
-    time.sleep(0.01)  # Try to wait for the sleep task to get scheduled.
+    ray.experimental.signal.receive([x_id])  # Block until it is scheduled.
     # Get the PID of the other worker.
     worker_pid = ray.get(get_worker_pid.remote())