Fix dead loop in QueueProcessor (#763)

Signed-off-by: Yaoliang Chen <[email protected]>

Author: xuanyue202

jaeger-core/src/main/java/io/jaegertracing/internal/reporters/RemoteReporter.java

@@ -167,7 +167,7 @@ public void execute() throws SenderException {
    */
   @ToString
   class QueueProcessor implements Runnable {
-    private boolean open = true;
+    private volatile boolean open = true;
     private final Set<Class<?>> commandFailedBefore = new HashSet<Class<?>>();
 
     @Override