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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.client;
19  
20  import java.util.ArrayList;
21  import java.util.List;
22  import java.util.concurrent.CountDownLatch;
23  import java.util.concurrent.TimeUnit;
24  import java.util.concurrent.atomic.AtomicLong;
25  
26  import org.apache.commons.logging.Log;
27  import org.apache.commons.logging.LogFactory;
28  import org.apache.hadoop.conf.Configuration;
29  import org.apache.hadoop.hbase.HBaseTestingUtility;
30  import org.apache.hadoop.hbase.HConstants;
31  import org.apache.hadoop.hbase.ServerName;
32  import org.apache.hadoop.hbase.TableName;
33  import org.apache.hadoop.hbase.client.backoff.ClientBackoffPolicy;
34  import org.apache.hadoop.hbase.client.backoff.ExponentialClientBackoffPolicy;
35  import org.apache.hadoop.hbase.client.backoff.ServerStatistics;
36  import org.apache.hadoop.hbase.client.coprocessor.Batch;
37  import org.apache.hadoop.hbase.regionserver.HRegion;
38  import org.apache.hadoop.hbase.regionserver.HRegionServer;
39  import org.apache.hadoop.hbase.testclassification.MediumTests;
40  import org.apache.hadoop.hbase.util.Bytes;
41  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
42  import org.junit.AfterClass;
43  import org.junit.BeforeClass;
44  import org.junit.Test;
45  import org.junit.experimental.categories.Category;
46  
47  import static org.junit.Assert.assertEquals;
48  import static org.junit.Assert.assertNotEquals;
49  import static org.junit.Assert.assertNotNull;
50  import static org.junit.Assert.assertTrue;
51  
52  /**
53   * Test that we can actually send and use region metrics to slowdown client writes
54   */
55  @Category(MediumTests.class)
56  public class TestClientPushback {
57  
58    private static final Log LOG = LogFactory.getLog(TestClientPushback.class);
59    private static final HBaseTestingUtility UTIL = new HBaseTestingUtility();
60  
61    private static final byte[] tableName = Bytes.toBytes("client-pushback");
62    private static final byte[] family = Bytes.toBytes("f");
63    private static final byte[] qualifier = Bytes.toBytes("q");
64    private static long flushSizeBytes = 1024;
65  
66    @BeforeClass
67    public static void setupCluster() throws Exception{
68      Configuration conf = UTIL.getConfiguration();
69      // enable backpressure
70      conf.setBoolean(HConstants.ENABLE_CLIENT_BACKPRESSURE, true);
71      // use the exponential backoff policy
72      conf.setClass(ClientBackoffPolicy.BACKOFF_POLICY_CLASS, ExponentialClientBackoffPolicy.class,
73        ClientBackoffPolicy.class);
74      // turn the memstore size way down so we don't need to write a lot to see changes in memstore
75      // load
76      conf.setLong(HConstants.HREGION_MEMSTORE_FLUSH_SIZE, flushSizeBytes);
77      // ensure we block the flushes when we are double that flushsize
78      conf.setLong("hbase.hregion.memstore.block.multiplier", 2);
79  
80      UTIL.startMiniCluster(1);
81      UTIL.createTable(tableName, family);
82    }
83  
84    @AfterClass
85    public static void teardownCluster() throws Exception{
86      UTIL.shutdownMiniCluster();
87    }
88  
89    @Test(timeout=60000)
90    public void testClientTracksServerPushback() throws Exception{
91      Configuration conf = UTIL.getConfiguration();
92      TableName tablename = TableName.valueOf(tableName);
93      // Cast also verifies HConnectionManager is creating connection instances
94      // of the correct type
95      HConnection conn = HConnectionManager.createConnection(conf);
96      HTable table = (HTable) conn.getTable(tablename);
97  
98      HRegionServer rs = UTIL.getHBaseCluster().getRegionServer(0);
99      HRegion region = rs.getOnlineRegions(tablename).get(0);
100 
101     LOG.debug("Writing some data to "+tablename);
102     // write some data
103     Put p = new Put(Bytes.toBytes("row"));
104     p.add(family, qualifier, Bytes.toBytes("value1"));
105     table.put(p);
106     table.flushCommits();
107 
108     // get the current load on RS. Hopefully memstore isn't flushed since we wrote the the data
109     int load = (int)((region.addAndGetGlobalMemstoreSize(0) * 100) / flushSizeBytes);
110     LOG.debug("Done writing some data to "+tablename);
111 
112     // get the stats for the region hosting our table
113     ClientBackoffPolicy backoffPolicy = conn.getBackoffPolicy();
114     assertTrue("Backoff policy is not correctly configured",
115       backoffPolicy instanceof ExponentialClientBackoffPolicy);
116     
117     ServerStatisticTracker stats = conn.getStatisticsTracker();
118     assertNotNull( "No stats configured for the client!", stats);
119     // get the names so we can query the stats
120     ServerName server = rs.getServerName();
121     byte[] regionName = region.getRegionName();
122 
123     // check to see we found some load on the memstore
124     ServerStatistics serverStats = stats.getServerStatsForTesting(server);
125     ServerStatistics.RegionStatistics regionStats = serverStats.getStatsForRegion(regionName);
126     assertEquals("We did not find some load on the memstore", load,
127       regionStats.getMemstoreLoadPercent());
128 
129     // check that the load reported produces a nonzero delay
130     long backoffTime = backoffPolicy.getBackoffTime(server, regionName, serverStats);
131     assertNotEquals("Reported load does not produce a backoff", backoffTime, 0);
132     LOG.debug("Backoff calculated for " + region.getRegionNameAsString() + " @ " + server +
133       " is " + backoffTime);
134 
135     // Reach into the connection and submit work directly to AsyncProcess so we can
136     // monitor how long the submission was delayed via a callback
137     List<Row> ops = new ArrayList<Row>(1);
138     p = new Put(Bytes.toBytes("row"));
139     p.add(family, qualifier, Bytes.toBytes("value2"));
140     ops.add(p);
141     final CountDownLatch latch = new CountDownLatch(1);
142     final AtomicLong endTime = new AtomicLong();
143     long startTime = EnvironmentEdgeManager.currentTimeMillis();
144     table.ap.submit(ops, true, new Batch.Callback<Object>() {
145       @Override
146       public void update(byte[] region, byte[] row, Object result) {
147         endTime.set(EnvironmentEdgeManager.currentTimeMillis());
148         latch.countDown();
149       }
150     });
151 
152     // Currently the ExponentialClientBackoffPolicy under these test conditions   
153     // produces a backoffTime of 151 milliseconds. This is long enough so the
154     // wait and related checks below are reasonable. Revisit if the backoff
155     // time reported by above debug logging has significantly deviated.
156     latch.await(backoffTime * 2, TimeUnit.MILLISECONDS);
157     assertNotEquals("AsyncProcess did not submit the work in time", endTime.get(), 0);
158     assertTrue("AsyncProcess did not delay long enough", endTime.get() - startTime >= backoffTime);
159   }
160 }