HDFS-8046. Allow better control of getContentSummary. Contributed by Kihwal Lee.

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

@@ -394,6 +394,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-8085. Move CorruptFileBlockIterator to a new hdfs.client.impl package.
     (szetszwo)
 
+    HDFS-8046. Allow better control of getContentSummary (kihwal)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -199,7 +199,9 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_LIST_LIMIT = "dfs.ls.limit";
   public static final int     DFS_LIST_LIMIT_DEFAULT = 1000;
   public static final String  DFS_CONTENT_SUMMARY_LIMIT_KEY = "dfs.content-summary.limit";
-  public static final int     DFS_CONTENT_SUMMARY_LIMIT_DEFAULT = 0;
+  public static final int     DFS_CONTENT_SUMMARY_LIMIT_DEFAULT = 5000;
+  public static final String  DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_KEY = "dfs.content-summary.sleep-microsec";
+  public static final long    DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_DEFAULT = 500;
   public static final String  DFS_DATANODE_FAILED_VOLUMES_TOLERATED_KEY = "dfs.datanode.failed.volumes.tolerated";
   public static final int     DFS_DATANODE_FAILED_VOLUMES_TOLERATED_DEFAULT = 0;
   public static final String  DFS_DATANODE_SYNCONCLOSE_KEY = "dfs.datanode.synconclose";

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ContentSummaryComputationContext.java

@@ -32,6 +32,8 @@ public class ContentSummaryComputationContext {
   private long nextCountLimit = 0;
   private long limitPerRun = 0;
   private long yieldCount = 0;
+  private long sleepMilliSec = 0;
+  private int sleepNanoSec = 0;
 
   /**
    * Constructor
@@ -43,17 +45,19 @@ public class ContentSummaryComputationContext {
    *        no limit (i.e. no yielding)
    */
   public ContentSummaryComputationContext(FSDirectory dir,
-      FSNamesystem fsn, long limitPerRun) {
+      FSNamesystem fsn, long limitPerRun, long sleepMicroSec) {
     this.dir = dir;
     this.fsn = fsn;
     this.limitPerRun = limitPerRun;
     this.nextCountLimit = limitPerRun;
     this.counts = new ContentCounts.Builder().build();
+    this.sleepMilliSec = sleepMicroSec/1000;
+    this.sleepNanoSec = (int)((sleepMicroSec%1000)*1000);
   }
 
   /** Constructor for blocking computation. */
   public ContentSummaryComputationContext(BlockStoragePolicySuite bsps) {
-    this(null, null, 0);
+    this(null, null, 0, 1000);
     this.bsps = bsps;
   }
 
@@ -105,7 +109,7 @@ public class ContentSummaryComputationContext {
     fsn.readUnlock();
 
     try {
-      Thread.sleep(1);
+      Thread.sleep(sleepMilliSec, sleepNanoSec);
     } catch (InterruptedException ie) {
     } finally {
       // reacquire

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java

@@ -496,7 +496,7 @@ class FSDirStatAndListingOp {
         // processed. 0 means disabled. I.e. blocking for the entire duration.
         ContentSummaryComputationContext cscc =
             new ContentSummaryComputationContext(fsd, fsd.getFSNamesystem(),
-                fsd.getContentCountLimit());
+                fsd.getContentCountLimit(), fsd.getContentSleepMicroSec());
         ContentSummary cs = targetNode.computeAndConvertContentSummary(cscc);
         fsd.addYieldCount(cscc.getYieldCount());
         return cs;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java

@@ -136,6 +136,7 @@ public class FSDirectory implements Closeable {
   private final int maxDirItems;
   private final int lsLimit;  // max list limit
   private final int contentCountLimit; // max content summary counts per run
+  private final long contentSleepMicroSec;
   private final INodeMap inodeMap; // Synchronized by dirLock
   private long yieldCount = 0; // keep track of lock yield count.
 
@@ -264,6 +265,9 @@ public class FSDirectory implements Closeable {
     this.contentCountLimit = conf.getInt(
         DFSConfigKeys.DFS_CONTENT_SUMMARY_LIMIT_KEY,
         DFSConfigKeys.DFS_CONTENT_SUMMARY_LIMIT_DEFAULT);
+    this.contentSleepMicroSec = conf.getLong(
+        DFSConfigKeys.DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_KEY,
+        DFSConfigKeys.DFS_CONTENT_SUMMARY_SLEEP_MICROSEC_DEFAULT);
     
     // filesystem limits
     this.maxComponentLength = conf.getInt(
@@ -345,6 +349,10 @@ public class FSDirectory implements Closeable {
     return contentCountLimit;
   }
 
+  long getContentSleepMicroSec() {
+    return contentSleepMicroSec;
+  }
+
   int getInodeXAttrsLimit() {
     return inodeXAttrsLimit;
   }