YARN-9806. TestNMSimulator#testNMSimulator fails in branch-2

hadoop-tools/hadoop-sls/src/test/java/org/apache/hadoop/yarn/sls/nodemanager/TestNMSimulator.java

@@ -17,6 +17,8 @@
  */
 package org.apache.hadoop.yarn.sls.nodemanager;
 
+import com.google.common.base.Supplier;
+import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.yarn.api.records.Container;
 import org.apache.hadoop.yarn.api.records.ContainerId;
 import org.apache.hadoop.yarn.conf.YarnConfiguration;
@@ -88,6 +90,13 @@ public class TestNMSimulator {
       numClusterNodes = rm.getResourceScheduler().getNumClusterNodes();
     }
 
+    GenericTestUtils.waitFor(new Supplier<Boolean>() {
+      @Override public Boolean get() {
+        return rm.getResourceScheduler().getRootQueueMetrics()
+            .getAvailableMB() > 0;
+      }
+    }, 500, 10000);
+
     Assert.assertEquals(1, rm.getResourceScheduler().getNumClusterNodes());
     Assert.assertEquals(GB * 10,
         rm.getResourceScheduler().getRootQueueMetrics().getAvailableMB());