Avoid UUID.randomUUID() in Verticle deployment startup code

This is done because bootstrapping the plumbing
needed by the JDK to produce a UUID value
is expensive, it thus doesn't make sense to
pay this cost when the property isn't actually
needed

vertx-core/src/main/java/io/vertx/core/impl/deployment/DefaultDeploymentManager.java

@@ -19,6 +19,7 @@
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  * @author <a href="http://tfox.org">Tim Fox</a>
@@ -27,6 +28,8 @@ public class DefaultDeploymentManager implements DeploymentManager {
 
   public static final Logger log = LoggerFactory.getLogger(DefaultDeploymentManager.class);
 
+  private static final AtomicLong nextId = new AtomicLong();
+
   private final VertxImpl vertx;
   private final Map<String, DeploymentContext> deploying = new HashMap<>();
   private final Map<String, DeploymentContext> deployments = new ConcurrentHashMap<>();
@@ -36,7 +39,11 @@ public DefaultDeploymentManager(VertxImpl vertx) {
   }
 
   private String generateDeploymentID() {
-    return UUID.randomUUID().toString();
+    if (vertx.isClustered() && vertx.haManager()!=null) {
+      // in this case we need a globally unique id
+      return UUID.randomUUID().toString();
+    }
+    return Long.valueOf(nextId.incrementAndGet()).toString();
   }
 
   public Future<Void> undeploy(String deploymentID) {