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From jdcry...@apache.org
Subject svn commit: r1352699 - in /hbase/trunk/hbase-server/src: main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java
Date Thu, 21 Jun 2012 21:26:57 GMT
Author: jdcryans
Date: Thu Jun 21 21:26:57 2012
New Revision: 1352699

URL: http://svn.apache.org/viewvc?rev=1352699&view=rev
Log:
HBASE-6207  Add jitter to client retry timer (Elliott Clark via JD)

Added:
    hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java
Modified:
    hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java

Modified: hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
URL: http://svn.apache.org/viewvc/hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java?rev=1352699&r1=1352698&r2=1352699&view=diff
==============================================================================
--- hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
(original)
+++ hbase/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/client/ConnectionUtils.java
Thu Jun 21 21:26:57 2012
@@ -21,6 +21,7 @@ import org.apache.hadoop.classification.
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.hbase.HConstants;
 
+import java.util.Random;
 
 /**
  * Utility used by client connections such as {@link HConnection} and
@@ -29,6 +30,8 @@ import org.apache.hadoop.hbase.HConstant
 @InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class ConnectionUtils {
+
+  private static final Random RANDOM = new Random();
   /**
    * Calculate pause time.
    * Built on {@link HConstants#RETRY_BACKOFF}.
@@ -41,6 +44,9 @@ public class ConnectionUtils {
     if (ntries >= HConstants.RETRY_BACKOFF.length) {
       ntries = HConstants.RETRY_BACKOFF.length - 1;
     }
-    return pause * HConstants.RETRY_BACKOFF[ntries];
+
+    long normalPause = pause * HConstants.RETRY_BACKOFF[ntries];
+    long jitter =  (long)(normalPause * RANDOM.nextFloat() * 0.01f); // 1% possible jitter
+    return normalPause + jitter;
   }
 }
\ No newline at end of file

Added: hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java
URL: http://svn.apache.org/viewvc/hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java?rev=1352699&view=auto
==============================================================================
--- hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java
(added)
+++ hbase/trunk/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestConnectionUtils.java
Thu Jun 21 21:26:57 2012
@@ -0,0 +1,56 @@
+/**
+ * Copyright The Apache Software Foundation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.client;
+
+import org.apache.hadoop.hbase.SmallTests;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+import java.util.Set;
+import java.util.TreeSet;
+
+import static org.junit.Assert.assertTrue;
+
+@Category(SmallTests.class)
+public class TestConnectionUtils {
+
+  @Test
+  public void testRetryTimeJitter() {
+    long[] retries = new long[200];
+    long baseTime = 1000000;  //Larger number than reality to help test randomness.
+    long maxTimeExpected = (long) (baseTime * 1.01f);
+    for (int i = 0; i < retries.length; i++) {
+      retries[i] = ConnectionUtils.getPauseTime(baseTime, 0);
+    }
+
+    Set<Long> retyTimeSet = new TreeSet<Long>();
+    for (long l : retries) {
+      /*make sure that there is some jitter but only 1%*/
+      assertTrue(l >= baseTime);
+      assertTrue(l <= maxTimeExpected);
+      // Add the long to the set
+      retyTimeSet.add(l);
+    }
+
+    //Make sure that most are unique.  some overlap will happen
+    assertTrue(retyTimeSet.size() > (retries.length * 0.80));
+  }
+
+}



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