Thread Pool: Add a dedicated thread pool for refresh, closes #1624.

src/main/java/org/elasticsearch/action/admin/indices/refresh/TransportRefreshAction.java

@@ -63,7 +63,7 @@ public class TransportRefreshAction extends TransportBroadcastOperationAction<Re
 
     @Override
     protected String executor() {
-        return ThreadPool.Names.MANAGEMENT;
+        return ThreadPool.Names.REFRESH;
     }
 
     @Override

src/main/java/org/elasticsearch/index/shard/service/InternalIndexShard.java

@@ -739,7 +739,7 @@ public class InternalIndexShard extends AbstractIndexShardComponent implements I
                 }
                 return;
             }
-            threadPool.cached().execute(new Runnable() {
+            threadPool.executor(ThreadPool.Names.REFRESH).execute(new Runnable() {
                 @Override
                 public void run() {
                     try {

src/main/java/org/elasticsearch/threadpool/ThreadPool.java

@@ -62,6 +62,7 @@ public class ThreadPool extends AbstractComponent {
         public static final String PERCOLATE = "percolate";
         public static final String MANAGEMENT = "management";
         public static final String MERGE = "merge";
+        public static final String REFRESH = "refresh";
         public static final String SNAPSHOT = "snapshot";
     }
 
@@ -88,6 +89,7 @@ public class ThreadPool extends AbstractComponent {
         executors.put(Names.PERCOLATE, build(Names.PERCOLATE, "cached", groupSettings.get(Names.PERCOLATE), ImmutableSettings.Builder.EMPTY_SETTINGS));
         executors.put(Names.MANAGEMENT, build(Names.MANAGEMENT, "scaling", groupSettings.get(Names.MANAGEMENT), settingsBuilder().put("keep_alive", "5m").put("size", 20).build()));
         executors.put(Names.MERGE, build(Names.MERGE, "scaling", groupSettings.get(Names.MERGE), settingsBuilder().put("keep_alive", "5m").put("size", 20).build()));
+        executors.put(Names.REFRESH, build(Names.REFRESH, "cached", groupSettings.get(Names.REFRESH), settingsBuilder().put("keep_alive", "1m").build()));
         executors.put(Names.SNAPSHOT, build(Names.SNAPSHOT, "scaling", groupSettings.get(Names.SNAPSHOT), ImmutableSettings.Builder.EMPTY_SETTINGS));
         executors.put(Names.SAME, new ExecutorHolder(MoreExecutors.sameThreadExecutor(), new Info(Names.SAME, "same")));
         this.executors = ImmutableMap.copyOf(executors);