View Javadoc

1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.regionserver;
20  
21  import java.io.IOException;
22  
23  import org.apache.commons.logging.Log;
24  import org.apache.commons.logging.LogFactory;
25  import org.apache.hadoop.hbase.classification.InterfaceAudience;
26  import org.apache.hadoop.hbase.DroppedSnapshotException;
27  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
28  import org.apache.hadoop.hbase.util.Bytes;
29  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
30  import org.apache.hadoop.ipc.RemoteException;
31  import org.apache.hadoop.util.StringUtils;
32  
33  import com.google.common.base.Preconditions;
34  
35  /**
36   * Handles processing region splits. Put in a queue, owned by HRegionServer.
37   */
38  @InterfaceAudience.Private
39  class SplitRequest implements Runnable {
40    private static final Log LOG = LogFactory.getLog(SplitRequest.class);
41    private final HRegion parent;
42    private final byte[] midKey;
43    private final HRegionServer server;
44    private TableLock tableLock;
45  
46    SplitRequest(Region region, byte[] midKey, HRegionServer hrs) {
47      Preconditions.checkNotNull(hrs);
48      this.parent = (HRegion)region;
49      this.midKey = midKey;
50      this.server = hrs;
51    }
52  
53    @Override
54    public String toString() {
55      return "regionName=" + parent + ", midKey=" + Bytes.toStringBinary(midKey);
56    }
57  
58    @Override
59    public void run() {
60      if (this.server.isStopping() || this.server.isStopped()) {
61        LOG.debug("Skipping split because server is stopping=" +
62          this.server.isStopping() + " or stopped=" + this.server.isStopped());
63        return;
64      }
65      boolean success = false;
66      server.metricsRegionServer.incrSplitRequest();
67      long startTime = EnvironmentEdgeManager.currentTime();
68      SplitTransactionImpl st = new SplitTransactionImpl(parent, midKey);
69      try {
70        //acquire a shared read lock on the table, so that table schema modifications
71        //do not happen concurrently
72        tableLock = server.getTableLockManager().readLock(parent.getTableDesc().getTableName()
73            , "SPLIT_REGION:" + parent.getRegionInfo().getRegionNameAsString());
74        try {
75          tableLock.acquire();
76        } catch (IOException ex) {
77          tableLock = null;
78          throw ex;
79        }
80  
81        // If prepare does not return true, for some reason -- logged inside in
82        // the prepare call -- we are not ready to split just now. Just return.
83        if (!st.prepare()) return;
84        try {
85          st.execute(this.server, this.server);
86          success = true;
87        } catch (Exception e) {
88          if (this.server.isStopping() || this.server.isStopped()) {
89            LOG.info(
90                "Skip rollback/cleanup of failed split of "
91                    + parent.getRegionInfo().getRegionNameAsString() + " because server is"
92                    + (this.server.isStopping() ? " stopping" : " stopped"), e);
93            return;
94          }
95          if (e instanceof DroppedSnapshotException) {
96            server.abort("Replay of WAL required. Forcing server shutdown", e);
97            return;
98          }
99          try {
100           LOG.info("Running rollback/cleanup of failed split of " +
101             parent.getRegionInfo().getRegionNameAsString() + "; " + e.getMessage(), e);
102           if (st.rollback(this.server, this.server)) {
103             LOG.info("Successful rollback of failed split of " +
104               parent.getRegionInfo().getRegionNameAsString());
105           } else {
106             this.server.abort("Abort; we got an error after point-of-no-return");
107           }
108         } catch (RuntimeException ee) {
109           String msg = "Failed rollback of failed split of " +
110             parent.getRegionInfo().getRegionNameAsString() + " -- aborting server";
111           // If failed rollback, kill this server to avoid having a hole in table.
112           LOG.info(msg, ee);
113           this.server.abort(msg + " -- Cause: " + ee.getMessage());
114         }
115         return;
116       }
117     } catch (IOException ex) {
118       ex = ex instanceof RemoteException ? ((RemoteException) ex).unwrapRemoteException() : ex;
119       LOG.error("Split failed " + this, ex);
120       server.checkFileSystem();
121     } finally {
122       if (this.parent.getCoprocessorHost() != null) {
123         try {
124           this.parent.getCoprocessorHost().postCompleteSplit();
125         } catch (IOException io) {
126           LOG.error("Split failed " + this,
127             io instanceof RemoteException ? ((RemoteException) io).unwrapRemoteException() : io);
128         }
129       }
130       if (parent.shouldForceSplit()) {
131         parent.clearSplit();
132       }
133       releaseTableLock();
134       long endTime = EnvironmentEdgeManager.currentTime();
135       // Update regionserver metrics with the split transaction total running time
136       server.metricsRegionServer.updateSplitTime(endTime - startTime);
137       if (success) {
138         server.metricsRegionServer.incrSplitSuccess();
139         // Log success
140         LOG.info("Region split, hbase:meta updated, and report to master. Parent="
141             + parent.getRegionInfo().getRegionNameAsString() + ", new regions: "
142             + st.getFirstDaughter().getRegionNameAsString() + ", "
143             + st.getSecondDaughter().getRegionNameAsString() + ". Split took "
144             + StringUtils.formatTimeDiff(EnvironmentEdgeManager.currentTime(), startTime));
145       }
146       // Always log the split transaction journal
147       LOG.info("Split transaction journal:\n\t" + StringUtils.join("\n\t", st.getJournal()));
148     }
149   }
150 
151   protected void releaseTableLock() {
152     if (this.tableLock != null) {
153       try {
154         this.tableLock.release();
155       } catch (IOException ex) {
156         LOG.error("Could not release the table lock (something is really wrong). "
157            + "Aborting this server to avoid holding the lock forever.");
158         this.server.abort("Abort; we got an error when releasing the table lock "
159                          + "on " + parent.getRegionInfo().getRegionNameAsString());
160       }
161     }
162   }
163 }