HDFS-9619. SimulatedFSDataset sometimes can not find blockpool for the correct namenode (Contributed by Wei-Chiu Chuang)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -2567,6 +2567,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9605. Add links to failed volumes to explorer.html in HDFS Web UI.
     (Archana T via wheat9)
 
+    HDFS-9619. SimulatedFSDataset sometimes can not find blockpool for the
+    correct namenode (Wei-Chiu Chuang via vinayakumarb)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/SimulatedFSDataset.java

@@ -29,6 +29,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 
 import javax.management.NotCompliantMBeanException;
 import javax.management.ObjectName;
@@ -521,7 +522,7 @@ public class SimulatedFSDataset implements FsDatasetSpi<FsVolumeSpi> {
   }
 
   private final Map<String, Map<Block, BInfo>> blockMap
-      = new HashMap<String, Map<Block,BInfo>>();
+      = new ConcurrentHashMap<String, Map<Block,BInfo>>();
   private final SimulatedStorage storage;
   private final SimulatedVolume volume;
   private final String datanodeUuid;

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestSimulatedFSDataset.java

@@ -27,6 +27,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+import org.apache.commons.lang.exception.ExceptionUtils;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.StorageType;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
@@ -38,6 +39,7 @@ import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaOutputStreams;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetFactory;
 import org.apache.hadoop.util.DataChecksum;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -338,4 +340,49 @@ public class TestSimulatedFSDataset {
     fsdataset.addBlockPool(bpid, conf);
     return fsdataset;
   }
+
+  @Test
+  public void testConcurrentAddBlockPool() throws InterruptedException,
+      IOException {
+    final String[] bpids = {"BP-TEST1-", "BP-TEST2-"};
+    final SimulatedFSDataset fsdataset = new SimulatedFSDataset(null, conf);
+    class AddBlockPoolThread extends Thread {
+      private int id;
+      private IOException ioe;
+      public AddBlockPoolThread(int id) {
+        super();
+        this.id = id;
+      }
+      public void test() throws InterruptedException, IOException {
+        this.join();
+        if (ioe != null) {
+          throw ioe;
+        }
+      }
+      public void run() {
+        for (int i=0; i < 10000; i++) {
+          // add different block pools concurrently
+          String newbpid = bpids[id] + i;
+          fsdataset.addBlockPool(newbpid, conf);
+          // and then add a block into the pool
+          ExtendedBlock block = new ExtendedBlock(newbpid,1);
+          try {
+            // it will throw an exception if the block pool is not found
+            fsdataset.createTemporary(StorageType.DEFAULT, block);
+          } catch (IOException ioe) {
+            // JUnit does not capture exception in non-main thread,
+            // so cache it and then let main thread throw later.
+            this.ioe = ioe;
+          }
+          assert(fsdataset.getReplicaString(newbpid,1) != "null");
+        }
+      }
+    };
+    AddBlockPoolThread t1 = new AddBlockPoolThread(0);
+    AddBlockPoolThread t2 = new AddBlockPoolThread(1);
+    t1.start();
+    t2.start();
+    t1.test();
+    t2.test();
+  }
 }