Add instance id suffix to Tomcat Engine name

Fixes gh-160

spring-boot/src/main/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainer.java

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.context.embedded.tomcat;
 
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.apache.catalina.Engine;
 import org.apache.catalina.LifecycleException;
 import org.apache.catalina.LifecycleState;
 import org.apache.catalina.connector.Connector;
@@ -39,7 +42,7 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 
 	private final Log logger = LogFactory.getLog(TomcatEmbeddedServletContainer.class);
 
-	private static int containerCounter = 0;
+	private static AtomicInteger containerCounter = new AtomicInteger(-1);
 
 	private final Tomcat tomcat;
 
@@ -66,6 +69,11 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 
 	private synchronized void initialize() throws EmbeddedServletContainerException {
 		try {
+			int instanceId = containerCounter.incrementAndGet();
+			if (instanceId > 0) {
+				Engine engine = this.tomcat.getEngine();
+				engine.setName(engine.getName() + "-" + instanceId);
+			}
 			this.tomcat.start();
 			try {
 				// Allow the server to start so the ServletContext is available, but stop
@@ -79,7 +87,7 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 			}
 			// Unlike Jetty, all Tomcat threads are daemon threads. We create a
 			// blocking non-daemon to stop immediate shutdown
-			Thread awaitThread = new Thread("container-" + (containerCounter++)) {
+			Thread awaitThread = new Thread("container-" + (containerCounter.get())) {
 				@Override
 				public void run() {
 					TomcatEmbeddedServletContainer.this.tomcat.getServer().await();
@@ -129,6 +137,9 @@ public class TomcatEmbeddedServletContainer implements EmbeddedServletContainer
 			throw new EmbeddedServletContainerException("Unable to stop embedded Tomcat",
 					ex);
 		}
+		finally {
+			containerCounter.decrementAndGet();
+		}
 	}
 
 	@Override

spring-boot/src/test/java/org/springframework/boot/context/embedded/tomcat/TomcatEmbeddedServletContainerFactoryTests.java

@@ -30,6 +30,7 @@ import org.mockito.InOrder;
 import org.springframework.boot.context.embedded.AbstractEmbeddedServletContainerFactoryTests;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThat;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.anyObject;
@@ -52,6 +53,20 @@ public class TomcatEmbeddedServletContainerFactoryTests extends
 		return new TomcatEmbeddedServletContainerFactory();
 	}
 
+	// JMX MBean names clash if you get more than one Engine with the same name...
+	@Test
+	public void tomcatEngineNames() throws Exception {
+		TomcatEmbeddedServletContainerFactory factory = getFactory();
+		this.container = factory.getEmbeddedServletContainer();
+		factory.setPort(8081);
+		TomcatEmbeddedServletContainer container2 = (TomcatEmbeddedServletContainer) factory
+				.getEmbeddedServletContainer();
+		assertEquals("Tomcat", ((TomcatEmbeddedServletContainer) this.container)
+				.getTomcat().getEngine().getName());
+		assertEquals("Tomcat-1", container2.getTomcat().getEngine().getName());
+		container2.stop();
+	}
+
 	@Test
 	public void tomcatListeners() throws Exception {
 		TomcatEmbeddedServletContainerFactory factory = getFactory();