[GitHub] [flink] wuchong commented on a change in pull request #14361: [FLINK-19435][connectors/jdbc] Fix deadlock when loading different driver classes concurrently using Class.forName

[GitBox <gi...@apache.org>]

wuchong commented on a change in pull request #14361:
URL: https://github.com/apache/flink/pull/14361#discussion_r545733120



##########
File path: flink-connectors/flink-connector-jdbc/src/test/java/org/apache/flink/connector/jdbc/internal/connection/SimpleJdbcConnectionProviderDriverClassConcurrentLoadingTest.java
##########
@@ -0,0 +1,102 @@
+/*
+ * 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.connector.jdbc.internal.connection;
+
+import org.apache.flink.connector.jdbc.JdbcConnectionOptions;
+import org.apache.flink.connector.jdbc.fakedb.FakeDBUtils;
+import org.apache.flink.core.testutils.CheckedThread;
+
+import org.junit.Test;
+
+import java.lang.reflect.Method;
+import java.sql.Connection;
+import java.util.concurrent.CountDownLatch;
+import java.util.function.Function;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * This test deals with sql driver class loading issues, write it alone so it won't be
+ * interfered by other tests.
+ */
+public class SimpleJdbcConnectionProviderDriverClassConcurrentLoadingTest {
+	private static boolean isClassLoaded(ClassLoader classLoader, String className) throws Exception {
+		do {
+			Method m = ClassLoader.class.getDeclaredMethod("findLoadedClass", String.class);
+			m.setAccessible(true);
+			Object loadedClass = m.invoke(classLoader, className);
+			if (loadedClass != null) {
+				return true;
+			}
+			classLoader = classLoader.getParent();
+		} while (classLoader != null);
+		return false;
+	}
+
+	@Test

Review comment:
       Would be better to add a timeout on the test, otherwise, it's hard to find which test eaten up the test time. 




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