HDFS-15406. Improve the speed of Datanode Block Scan. Contributed by hemanthboyina

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java

@@ -133,6 +133,7 @@ public class FsVolumeImpl implements FsVolumeSpi {
   protected volatile long configuredCapacity;
   private final FileIoProvider fileIoProvider;
   private final DataNodeVolumeMetrics metrics;
+  private URI baseURI;
 
   /**
    * Per-volume worker pool that processes new blocks to cache.
@@ -182,6 +183,7 @@ public class FsVolumeImpl implements FsVolumeSpi {
       File parent = currentDir.getParentFile();
       cacheExecutor = initializeCacheExecutor(parent);
       this.metrics = DataNodeVolumeMetrics.create(conf, parent.getPath());
+      this.baseURI = new File(currentDir.getParent()).toURI();
     } else {
       cacheExecutor = null;
       this.metrics = null;
@@ -506,7 +508,7 @@ public class FsVolumeImpl implements FsVolumeSpi {
 
   @Override
   public URI getBaseURI() {
-    return new File(currentDir.getParent()).toURI();
+    return baseURI;
   }
 
   @Override

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

@@ -239,7 +239,7 @@ public class DataNodeTestUtils {
     try (FsDatasetSpi.FsVolumeReferences volumes = dn.getFSDataset()
         .getFsVolumeReferences()) {
       for (FsVolumeSpi vol : volumes) {
-        if (vol.getBaseURI().equals(basePath.toURI())) {
+        if (new File(vol.getBaseURI()).equals(basePath)) {
           return (FsVolumeImpl) vol;
         }
       }