The queue_size value should be shown as an integer,

closes #10404
closes #13063

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

@@ -727,7 +727,7 @@ public class ThreadPool extends AbstractComponent {
             if (queueSize == null) {
                 builder.field(Fields.QUEUE_SIZE, -1);
             } else {
-                builder.field(Fields.QUEUE_SIZE, queueSize.toString());
+                builder.field(Fields.QUEUE_SIZE, queueSize.singles());
             }
             builder.endObject();
             return builder;

core/src/test/java/org/elasticsearch/threadpool/ThreadPoolSerializationTests.java

@@ -99,4 +99,23 @@ public class ThreadPoolSerializationTests extends ESTestCase {
         assertThat(threadPool.info("index").getQueueSize(), is(nullValue()));
         terminate(threadPool);
     }
+
+    @Test
+    public void testThatToXContentWritesInteger() throws Exception {
+        ThreadPool.Info info = new ThreadPool.Info("foo", "search", 1, 10, TimeValue.timeValueMillis(3000), SizeValue.parseSizeValue("1k"));
+        XContentBuilder builder = jsonBuilder();
+        builder.startObject();
+        info.toXContent(builder, ToXContent.EMPTY_PARAMS);
+        builder.endObject();
+
+        BytesReference bytesReference = builder.bytes();
+        Map<String, Object> map;
+        try (XContentParser parser = XContentFactory.xContent(bytesReference).createParser(bytesReference)) {
+            map = parser.map();
+        }
+        assertThat(map, hasKey("foo"));
+        map = (Map<String, Object>) map.get("foo");
+        assertThat(map, hasKey("queue_size"));
+        assertThat(map.get("queue_size").toString(), is("1000"));
+    }
 }

docs/reference/migration/migrate_2_0/stats.asciidoc

@@ -55,3 +55,7 @@ headers by default. Verbosity can be turned off with the `v` parameter:
 GET _cat/shards?v=0
 -----------------
 
+==== Nodes Stats API
+
+Queue lengths are now reported as basic numeric so they can easily processed by code. Before we used a human
+readable format. For example, a queue with 1,000 items is now reported as `1000` instead of `1k`.