[client] Wait for status thread to properly exit in shutdown sequence

core/src/main/java/com/yahoo/ycsb/Client.java

@@ -800,7 +800,13 @@ public class Client
 
 		if (status)
 		{
-			statusthread.interrupt();
+		    // wake up status thread if it's asleep
+		    statusthread.interrupt();
+		    // at this point we assume all the monitored threads are already gone as per above join loop.
+			try {
+                statusthread.join();
+            } catch (InterruptedException e) {
+            }
 		}
 
 		try