Fix unit tests and GC settings for Java 15 (#11074)

* JavaScript script engine support was removed in JDK 15: skip those tests for JDKs without it
* Fix flaky HTTP client tests with Java 15
* Switch from CMS to G1GC in integration tests, since CMS is no longer available in JDK 15

core/src/test/java/org/apache/druid/java/util/http/client/JankyServersTest.java

@@ -41,6 +41,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.net.ServerSocket;
 import java.net.Socket;
+import java.net.SocketException;
 import java.net.URL;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
@@ -298,6 +299,7 @@ public class JankyServersTest
   public boolean isChannelClosedException(Throwable e)
   {
     return e instanceof ChannelException ||
+           (e instanceof SocketException && e.getMessage().contains("Connection reset")) ||
            (e instanceof IOException && e.getMessage().contains("Connection reset by peer"));
   }
 

indexing-service/src/test/java/org/apache/druid/indexing/overlord/setup/JavaScriptWorkerSelectStrategyTest.java

@@ -32,10 +32,14 @@ import org.easymock.EasyMock;
 import org.hamcrest.CoreMatchers;
 import org.joda.time.Period;
 import org.junit.Assert;
+import org.junit.Assume;
+import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
+import javax.script.ScriptEngineManager;
+
 public class JavaScriptWorkerSelectStrategyTest
 {
   @Rule
@@ -71,6 +75,13 @@ public class JavaScriptWorkerSelectStrategyTest
       JavaScriptConfig.getEnabledInstance()
   );
 
+  @Before
+  public void checkJdkCompatibility()
+  {
+    // skip tests for newer JDKs without javascript support
+    Assume.assumeNotNull(new ScriptEngineManager().getEngineByName("javascript"));
+  }
+
   @Test
   public void testSerde() throws Exception
   {

integration-tests/docker/environment-configs/router-custom-check-tls

@@ -21,7 +21,7 @@ DRUID_SERVICE=router
 DRUID_LOG_PATH=/shared/logs/router-custom-check-tls.log
 
 # JAVA OPTS
-SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5003
+SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseG1GC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5003
 
 # Druid configs
 druid_plaintextPort=8891

integration-tests/docker/environment-configs/router-no-client-auth-tls

@@ -21,7 +21,7 @@ DRUID_SERVICE=router
 DRUID_LOG_PATH=/shared/logs/router-no-client-auth-tls.log
 
 # JAVA OPTS
-SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5002
+SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseG1GC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5002
 
 # Druid configs
 druid_plaintextPort=8890

integration-tests/docker/environment-configs/router-permissive-tls

@@ -21,7 +21,7 @@ DRUID_SERVICE=router
 DRUID_LOG_PATH=/shared/logs/router-permissive-tls.log
 
 # JAVA OPTS
-SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5001
+SERVICE_DRUID_JAVA_OPTS=-server -Xmx64m -Xms64m -XX:+UseG1GC -XX:+PrintGCDetails -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5001
 
 # Druid configs
 druid_plaintextPort=8889

server/src/test/java/org/apache/druid/server/router/JavaScriptTieredBrokerSelectorStrategyTest.java

@@ -32,10 +32,13 @@ import org.apache.druid.query.aggregation.LongSumAggregatorFactory;
 import org.apache.druid.query.topn.TopNQueryBuilder;
 import org.hamcrest.CoreMatchers;
 import org.junit.Assert;
+import org.junit.Assume;
+import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 
+import javax.script.ScriptEngineManager;
 import java.util.LinkedHashMap;
 
 public class JavaScriptTieredBrokerSelectorStrategyTest
@@ -48,6 +51,13 @@ public class JavaScriptTieredBrokerSelectorStrategyTest
       JavaScriptConfig.getEnabledInstance()
   );
 
+  @Before
+  public void checkJdkCompatibility()
+  {
+    // skip tests for newer JDKs without javascript support
+    Assume.assumeNotNull(new ScriptEngineManager().getEngineByName("javascript"));
+  }
+
   @Test
   public void testSerde() throws Exception
   {