Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/4364#discussion_r128475216
--- Diff:
flink-runtime/src/test/java/org/apache/flink/runtime/executiongraph/restart/FailureRateRestartStrategyTest.java
---
@@ -0,0 +1,128 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.executiongraph.restart;
+
+import org.apache.flink.api.common.time.Time;
+import org.apache.flink.core.testutils.OneShotLatch;
+import org.apache.flink.runtime.concurrent.ScheduledExecutor;
+import org.apache.flink.runtime.concurrent.ScheduledExecutorServiceAdapter;
+
+import org.junit.After;
+import org.junit.Test;
+
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Unit test for the {@link FailureRateRestartStrategy}.
+ */
+public class FailureRateRestartStrategyTest {
+
+ public final ScheduledExecutorService executorService =
Executors.newScheduledThreadPool(4);
+
+ public final ScheduledExecutor executor = new
ScheduledExecutorServiceAdapter(executorService);
+
+ @After
+ public void shutdownExecutor() {
+ executorService.shutdownNow();
+ }
+
+ //
------------------------------------------------------------------------
+
+ @Test
+ public void testManyFailuresWithinRate() throws Exception {
+ final int numAttempts = 10;
+ final int intervalMillis = 1;
+
+ final FailureRateRestartStrategy restartStrategy =
+ new FailureRateRestartStrategy(1,
Time.milliseconds(intervalMillis), Time.milliseconds(0));
+
+ for (int attempsLeft = numAttempts; attempsLeft > 0;
--attempsLeft) {
+ assertTrue(restartStrategy.canRestart());
+ restartStrategy.restart(new NoOpRestarter(), executor);
+ sleepGuaranteed(2 * intervalMillis);
+ }
+
+ assertTrue(restartStrategy.canRestart());
+ }
+
+ @Test
+ public void testFailuresExceedingRate() throws Exception {
+ final int numFailures = 3;
+ final int intervalMillis = 10_000;
+
+ final FailureRateRestartStrategy restartStrategy =
+ new FailureRateRestartStrategy(numFailures,
Time.milliseconds(intervalMillis), Time.milliseconds(0));
+
+ for (int failuresLeft = numFailures; failuresLeft > 0;
--failuresLeft) {
+ assertTrue(restartStrategy.canRestart());
+ restartStrategy.restart(new NoOpRestarter(), executor);
+ }
+
+ // now the rate should be exceeded
+ assertFalse(restartStrategy.canRestart());
+ }
+
+ @Test
+ public void testDelay() throws Exception {
+ final long restartDelay = 2;
+ final int numberRestarts = 10;
+
+ final FailureRateRestartStrategy strategy =
+ new FailureRateRestartStrategy(numberRestarts + 1,
Time.milliseconds(1), Time.milliseconds(restartDelay));
+
+ for (int restartsLeft = numberRestarts; restartsLeft > 0;
--restartsLeft) {
+ assertTrue(strategy.canRestart());
+
+ final OneShotLatch sync = new OneShotLatch();
+ final RestartCallback restarter = new
LatchedRestarter(sync);
+
+ final long time = System.nanoTime();
+ strategy.restart(restarter, executor);
+ sync.await();
+
+ final long elapsed = System.nanoTime() - time;
+ assertTrue("Not enough delay", elapsed >= restartDelay
* 1_000_000);
+ }
+ }
+
+ //
------------------------------------------------------------------------
+
+ /**
+ * This method makes sure that the actual interval and is not
spuriously waking up.
--- End diff --
"This method makes sure to sleep for the required interval and that we
don't spuriously wake up."?
Also, what happens if `Thread.sleep()` is interrupted?
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