Cluster Utilities for Fault Tolerance Tests (#3008)

test/multi_node_test_2.py

@@ -0,0 +1,72 @@
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import logging
+import os
+import pytest
+
+import ray
+import ray.services as services
+from ray.test.cluster_utils import Cluster
+
+logger = logging.getLogger(__name__)
+
+
+@pytest.fixture
+def start_connected_cluster():
+    # Start the Ray processes.
+    g = Cluster(initialize_head=True, connect=True)
+    yield g
+    # The code after the yield will run as teardown code.
+    ray.shutdown()
+    g.shutdown()
+
+
+@pytest.mark.skipif(
+    os.environ.get("RAY_USE_XRAY") != "1",
+    reason="This test only works with xray.")
+def test_cluster():
+    """Basic test for adding and removing nodes in cluster."""
+    g = Cluster(initialize_head=False)
+    node = g.add_node()
+    node2 = g.add_node()
+    assert node.all_processes_alive()
+    assert node2.all_processes_alive()
+    g.remove_node(node2)
+    g.remove_node(node)
+    assert not any(node.any_processes_alive() for node in g.list_all_nodes())
+
+
+@pytest.mark.skipif(
+    os.environ.get("RAY_USE_XRAY") != "1",
+    reason="This test only works with xray.")
+def test_wait_for_nodes(start_connected_cluster):
+    """Unit test for `Cluster.wait_for_nodes`.
+
+    Adds 4 workers, waits, then removes 4 workers, waits,
+    then adds 1 worker, waits, and removes 1 worker, waits.
+    """
+    cluster = start_connected_cluster
+    workers = [cluster.add_node() for i in range(4)]
+    cluster.wait_for_nodes()
+    [cluster.remove_node(w) for w in workers]
+    cluster.wait_for_nodes()
+    worker2 = cluster.add_node()
+    cluster.wait_for_nodes()
+    cluster.remove_node(worker2)
+    cluster.wait_for_nodes()
+
+
+@pytest.mark.skipif(
+    os.environ.get("RAY_USE_XRAY") != "1",
+    reason="This test only works with xray.")
+def test_worker_plasma_store_failure(start_connected_cluster):
+    cluster = start_connected_cluster
+    worker = cluster.add_node()
+    cluster.wait_for_nodes()
+    # Log monitor doesn't die for some reason
+    worker.kill_log_monitor()
+    worker.kill_plasma_store()
+    worker.process_dict[services.PROCESS_TYPE_RAYLET][0].wait()
+    assert not worker.any_processes_alive(), worker.live_processes()