THRIFT-4469: Make isServing volatile
diff --git a/lib/java/src/org/apache/thrift/server/TServer.java b/lib/java/src/org/apache/thrift/server/TServer.java
index 80f4f86..bac06b2 100644
--- a/lib/java/src/org/apache/thrift/server/TServer.java
+++ b/lib/java/src/org/apache/thrift/server/TServer.java
@@ -123,7 +123,7 @@
    */
   protected TProtocolFactory outputProtocolFactory_;
 
-  private boolean isServing;
+  private volatile boolean isServing;
 
   protected TServerEventHandler eventHandler_;