HBASE-21102 - ServerCrashProcedure should select target server where no

other replicas exist for the current region -  fix flaky test (Ram)

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStates.java

@@ -37,9 +37,11 @@ import org.apache.hadoop.hbase.HRegionLocation;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.client.RegionReplicaUtil;
 import org.apache.hadoop.hbase.master.RegionState;
 import org.apache.hadoop.hbase.master.RegionState.State;
 import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.ServerRegionReplicaUtil;
 import org.apache.yetus.audience.InterfaceAudience;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -772,6 +774,26 @@ public class RegionStates {
     return serverNode;
   }
 
+  public boolean isReplicaAvailableForRegion(final RegionInfo info) {
+    // if the region info itself is a replica return true.
+    if (!RegionReplicaUtil.isDefaultReplica(info)) {
+      return true;
+    }
+    // iterate the regionsMap for the given region name. If there are replicas it should
+    // list them in order.
+    for (RegionStateNode node : regionsMap.tailMap(info.getRegionName()).values()) {
+      if (!node.getTable().equals(info.getTable())
+          || !ServerRegionReplicaUtil.isReplicasForSameRegion(info, node.getRegionInfo())) {
+        break;
+      } else if (!RegionReplicaUtil.isDefaultReplica(node.getRegionInfo())) {
+        // we have replicas
+        return true;
+      }
+    }
+    // we don have replicas
+    return false;
+  }
+
   public ServerStateNode removeRegionFromServer(final ServerName serverName,
       final RegionStateNode regionNode) {
     ServerStateNode serverNode = getOrCreateServer(serverName);

hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java

@@ -34,6 +34,7 @@ import java.util.Set;
 import java.util.TreeMap;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
+
 import org.apache.commons.lang3.NotImplementedException;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.ClusterMetrics;
@@ -51,15 +52,14 @@ import org.apache.hadoop.hbase.master.MasterServices;
 import org.apache.hadoop.hbase.master.RackManager;
 import org.apache.hadoop.hbase.master.RegionPlan;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.Action.Type;
-import org.apache.yetus.audience.InterfaceAudience;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
 import org.apache.hbase.thirdparty.com.google.common.base.Joiner;
 import org.apache.hbase.thirdparty.com.google.common.collect.ArrayListMultimap;
 import org.apache.hbase.thirdparty.com.google.common.collect.Lists;
 import org.apache.hbase.thirdparty.com.google.common.collect.Sets;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * The base class for load balancers. It provides the the functions used to by
@@ -1454,8 +1454,13 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
     for (Map.Entry<RegionInfo, ServerName> entry : regions.entrySet()) {
       RegionInfo region = entry.getKey();
       ServerName oldServerName = entry.getValue();
-      if (!hasRegionReplica && !RegionReplicaUtil.isDefaultReplica(region)) {
+      // In the current set of regions even if one has region replica let us go with
-        hasRegionReplica = true;
+      // getting the entire snapshot
+      if (this.services != null && this.services.getAssignmentManager() != null) { // for tests
+        if (!hasRegionReplica && this.services.getAssignmentManager().getRegionStates()
+            .isReplicaAvailableForRegion(region)) {
+          hasRegionReplica = true;
+        }
       }
       List<ServerName> localServers = new ArrayList<>();
       if (oldServerName != null) {