Use daemon threads for NodeChecker and IdleConnectionReaper.

jest-common/src/main/java/io/searchbox/client/config/discovery/NodeChecker.java

@@ -1,6 +1,8 @@
 package io.searchbox.client.config.discovery;
 
 import com.google.common.util.concurrent.AbstractScheduledService;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import io.searchbox.client.JestClient;
@@ -11,6 +13,9 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadFactory;
 import java.util.LinkedHashSet;
 import java.util.Map.Entry;
 import java.util.concurrent.TimeUnit;
@@ -91,6 +96,28 @@ protected Scheduler scheduler() {
         return scheduler;
     }
 
+    @Override
+    protected ScheduledExecutorService executor() {
+        final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(
+            new ThreadFactoryBuilder()
+                .setDaemon(true)
+                .setNameFormat(serviceName())
+                .build());
+        // Add a listener to shutdown the executor after the service is stopped.  This ensures that the
+        // JVM shutdown will not be prevented from exiting after this service has stopped or failed.
+        // Technically this listener is added after start() was called so it is a little gross, but it
+        // is called within doStart() so we know that the service cannot terminate or fail concurrently
+        // with adding this listener so it is impossible to miss an event that we are interested in.
+        addListener(new Listener() {
+            @Override public void terminated(State from) {
+                executor.shutdown();
+            }
+            @Override public void failed(State from, Throwable failure) {
+                executor.shutdown();
+            }}, MoreExecutors.sameThreadExecutor());
+        return executor;
+    }
+
     /**
      * Converts the Elasticsearch reported publish address in the format "inet[<hostname>:<port>]" or
      * "inet[<hostname>/<hostaddress>:<port>]" to a normalized http address in the form "http://host:port".

jest-common/src/main/java/io/searchbox/client/config/idle/IdleConnectionReaper.java

@@ -1,10 +1,16 @@
 package io.searchbox.client.config.idle;
 
 import com.google.common.util.concurrent.AbstractScheduledService;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import io.searchbox.client.config.ClientConfig;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadFactory;
+
 /**
  * Used to reap idle connections from the connection manager.
  */
@@ -33,4 +39,26 @@ protected Scheduler scheduler() {
                                                clientConfig.getMaxConnectionIdleTime(),
                                                clientConfig.getMaxConnectionIdleTimeDurationTimeUnit());
     }
+
+    @Override
+    protected ScheduledExecutorService executor() {
+        final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(
+            new ThreadFactoryBuilder()
+                .setDaemon(true)
+                .setNameFormat(serviceName())
+                .build());
+        // Add a listener to shutdown the executor after the service is stopped.  This ensures that the
+        // JVM shutdown will not be prevented from exiting after this service has stopped or failed.
+        // Technically this listener is added after start() was called so it is a little gross, but it
+        // is called within doStart() so we know that the service cannot terminate or fail concurrently
+        // with adding this listener so it is impossible to miss an event that we are interested in.
+        addListener(new Listener() {
+            @Override public void terminated(State from) {
+                executor.shutdown();
+            }
+            @Override public void failed(State from, Throwable failure) {
+                executor.shutdown();
+            }}, MoreExecutors.sameThreadExecutor());
+        return executor;
+    }
 }