Fix releasing CPUs incorrectly when actor creation task blocked. (#5271)

* Fix

* Remove useless log

* Address

* Fix typo

* sleep

python/ray/tests/test_dynres.py

@@ -569,3 +569,39 @@ def test_dynamic_res_creation_stress(ray_start_cluster):
             all_resources_created.append(str(i) in resources)
         success = all(all_resources_created)
     assert success
+
+
+def test_release_cpus_when_actor_creation_task_blocking(shutdown_only):
+    ray.init(num_cpus=2)
+
+    @ray.remote(num_cpus=1)
+    def get_100():
+        time.sleep(1)
+        return 100
+
+    @ray.remote(num_cpus=1)
+    class A(object):
+        def __init__(self):
+            self.num = ray.get(get_100.remote())
+
+        def get_num(self):
+            return self.num
+
+    a = A.remote()
+    assert 100 == ray.get(a.get_num.remote())
+
+    def wait_until(condition, timeout_ms):
+        SLEEP_DURATION_MS = 100
+        time_elapsed = 0
+        while time_elapsed <= timeout_ms:
+            if condition():
+                return True
+            time.sleep(SLEEP_DURATION_MS)
+            time_elapsed += SLEEP_DURATION_MS
+        return False
+
+    def assert_available_resources():
+        return 1 == ray.available_resources()["CPU"]
+
+    result = wait_until(assert_available_resources, 1000)
+    assert result is True