KAFKA-16072: JUnit 5 extension to detect thread leak

build.gradle

@@ -114,6 +114,8 @@ ext {
   repo = file("$rootDir/.git").isDirectory() ? Grgit.open(currentDir: project.getRootDir()) : null
 
   commitId = determineCommitId()
+
+  junitExtensionsAutodetectionEnabled = "junit.jupiter.extensions.autodetection.enabled"
 }
 
 allprojects {
@@ -439,6 +441,7 @@ subprojects {
       displayGranularity = 0
     }
     logTestStdout.rehydrate(delegate, owner, this)()
+    systemProperty(junitExtensionsAutodetectionEnabled, true)
 
     exclude testsToExclude
 
@@ -467,6 +470,7 @@ subprojects {
       displayGranularity = 0
     }
     logTestStdout.rehydrate(delegate, owner, this)()
+    systemProperty(junitExtensionsAutodetectionEnabled, true)
 
     exclude testsToExclude
 
@@ -510,6 +514,7 @@ subprojects {
       displayGranularity = 0
     }
     logTestStdout.rehydrate(delegate, owner, this)()
+    systemProperty(junitExtensionsAutodetectionEnabled, true)
 
     exclude testsToExclude
 

core/src/test/java/kafka/test/junit/LeakTestingExtension.java

@@ -0,0 +1,84 @@
+/*
+ * 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 kafka.test.junit;
+
+import kafka.utils.TestUtils;
+import org.junit.jupiter.api.extension.AfterEachCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.ExtensionContext.Namespace;
+import org.junit.jupiter.api.extension.ExtensionContext.Store;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+import scala.Tuple2;
+
+import static org.apache.kafka.test.TestUtils.DEFAULT_MAX_WAIT_MS;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class LeakTestingExtension implements BeforeEachCallback, AfterEachCallback {
+    private static final Set<String> EXPECTED_THREAD_NAMES = new HashSet<>(
+            Arrays.asList(
+                    "Attach Listener", "client-metrics-reaper", "executor-", "feature-zk-node-event-process-thread",
+                    "ForkJoinPool", "JMX", "junit-", "metrics-meter-tick-thread", "pool-", "process reaper", "RMI",
+                    "scala-"
+            )
+    );
+    private static final String THREADS_KEY = "threads";
+
+    @Override
+    public void beforeEach(ExtensionContext context) {
+        getStore(context).put(THREADS_KEY, Thread.getAllStackTraces().keySet());
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public void afterEach(ExtensionContext context) {
+        Set<Thread> initialThreads = getStore(context).remove(THREADS_KEY, Set.class);
+        Tuple2<Set<Thread>, Object> unexpectedThreads = TestUtils.computeUntilTrue(
+                () -> unexpectedThreads(initialThreads),
+                DEFAULT_MAX_WAIT_MS,
+                100L,
+                Set::isEmpty
+        );
+
+        assertTrue(unexpectedThreads._1.isEmpty(), "Found unexpected threads after executing test: " +
+                unexpectedThreads._1.stream().map(Objects::toString).collect(Collectors.joining(", ")));
+    }
+
+    private Set<Thread> unexpectedThreads(Set<Thread> initialThreads) {
+        Set<Thread> threads = new HashSet<>(Thread.getAllStackTraces().keySet());
+        return threads.stream()
+                .filter(t -> !initialThreads.contains(t))
+                .filter(t -> {
+                    for (String s: EXPECTED_THREAD_NAMES) {
+                        if (t.getName().contains(s))
+                            return false;
+                    }
+                    return true;
+                })
+                .collect(Collectors.toSet());
+    }
+
+    private Store getStore(ExtensionContext context) {
+        return context.getStore(Namespace.create(getClass(), context.getRequiredTestMethod()));
+    }
+}

core/src/test/resources/META-INF/services/org.junit.jupiter.api.extension.Extension

@@ -0,0 +1,16 @@
+ # 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.
+
+kafka.test.junit.LeakTestingExtension