YARN-11390. TestResourceTrackerService.testNodeRemovalNormally: Shutdown nodes should be 0 now expected: <1> but was: <0>

- The hardcoded sleep what was used in the test was not the most stable solution
- It was replaced with a polling assert

Author: K0K0V0K

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/TestResourceTrackerService.java

@@ -63,6 +63,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Supplier;
 import javax.xml.parsers.DocumentBuilderFactory;
@@ -2961,17 +2962,15 @@ protected ResourceTrackerService createResourceTrackerService() {
   }
 
   private void pollingAssert(Supplier<Boolean> supplier, String message)
-      throws InterruptedException {
-    pollingAssert(supplier, true, message);
+      throws InterruptedException, TimeoutException {
+    GenericTestUtils.waitFor(supplier,
+        100, 10_000, message);
   }
 
   private <T> void pollingAssert(Supplier<T> supplier, T expected, String message)
-      throws InterruptedException {
-    long timeOut = System.currentTimeMillis() + 10_000;
-    while (System.currentTimeMillis() < timeOut && !Objects.equals(expected, supplier.get())) {
-      Thread.sleep(100);
-    }
-    Assert.assertEquals(message, expected, supplier.get());
+      throws InterruptedException, TimeoutException {
+    GenericTestUtils.waitFor(() -> Objects.equals(supplier.get(), expected),
+        100, 10_000, message);
   }
 
   /**