HBASE-3323 OOME in master splitting logs

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1051278 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -797,6 +797,7 @@ Release 0.90.0 - Unreleased
    HBASE-3370  ReplicationSource.openReader fails to locate HLogs when they
                aren't split yet
    HBASE-3371  Race in TestReplication can make it fail
+   HBASE-3323  OOME in master splitting logs
 
 
   IMPROVEMENTS

src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java

@@ -190,12 +190,13 @@ public class MasterFileSystem {
     long splitTime = 0, splitLogSize = 0;
     Path logDir = new Path(this.rootdir, HLog.getHLogDirectoryName(serverName));
     try {
-      HLogSplitter splitter = HLogSplitter.createLogSplitter(conf);
+      HLogSplitter splitter = HLogSplitter.createLogSplitter(
+        conf, rootdir, logDir, oldLogDir, this.fs);
       try {
-        splitter.splitLog(this.rootdir, logDir, oldLogDir, this.fs, conf);
+        splitter.splitLog();
       } catch (OrphanHLogAfterSplitException e) {
         LOG.warn("Retrying splitting because of:", e);
-        splitter.splitLog(this.rootdir, logDir, oldLogDir, this.fs, conf);
+        splitter.splitLog();
       }
       splitTime = splitter.getTime();
       splitLogSize = splitter.getSize();

src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLog.java

@@ -1439,8 +1439,9 @@ public class HLog implements Syncable {
       throw new IOException(p + " is not a directory");
     }
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(baseDir, p, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(
+        conf, baseDir, p, oldLogDir, fs);
+    logSplitter.splitLog();
   }
 
   /**

src/main/java/org/apache/hadoop/hbase/regionserver/wal/HLogKey.java

@@ -160,6 +160,32 @@ public class HLogKey implements WritableComparable<HLogKey> {
     return result;
   }
 
+  /**
+   * Drop this instance's tablename byte array and instead
+   * hold a reference to the provided tablename. This is not
+   * meant to be a general purpose setter - it's only used
+   * to collapse references to conserve memory.
+   */
+  void internTableName(byte []tablename) {
+    // We should not use this as a setter - only to swap
+    // in a new reference to the same table name.
+    assert Bytes.equals(tablename, this.tablename);
+    this.tablename = tablename;
+  }
+
+  /**
+   * Drop this instance's region name byte array and instead
+   * hold a reference to the provided region name. This is not
+   * meant to be a general purpose setter - it's only used
+   * to collapse references to conserve memory.
+   */
+  void internEncodedRegionName(byte []encodedRegionName) {
+    // We should not use this as a setter - only to swap
+    // in a new reference to the same table name.
+    assert Bytes.equals(this.encodedRegionName, encodedRegionName);
+    this.encodedRegionName = encodedRegionName;
+  }
+
   public void write(DataOutput out) throws IOException {
     Bytes.writeByteArray(out, this.encodedRegionName);
     Bytes.writeByteArray(out, this.tablename);

src/main/java/org/apache/hadoop/hbase/regionserver/wal/WALEdit.java

@@ -27,6 +27,7 @@ import java.util.List;
 import java.util.NavigableMap;
 import java.util.TreeMap;
 
+import org.apache.hadoop.hbase.io.HeapSize;
 import org.apache.hadoop.hbase.KeyValue;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.ClassSize;
@@ -66,7 +67,7 @@ import org.apache.hadoop.io.Writable;
  * is an old style KeyValue or the new style WALEdit.
  *
  */
-public class WALEdit implements Writable {
+public class WALEdit implements Writable, HeapSize {
 
   private final int VERSION_2 = -1;
 
@@ -154,7 +155,19 @@ public class WALEdit implements Writable {
         out.writeInt(scopes.get(key));
       }
     }
+  }
 
+  public long heapSize() {
+    long ret = 0;
+    for (KeyValue kv : kvs) {
+      ret += kv.heapSize();
+    }
+    if (scopes != null) {
+      ret += ClassSize.TREEMAP;
+      ret += ClassSize.align(scopes.size() * ClassSize.MAP_ENTRY);
+      // TODO this isn't quite right, need help here
+    }
+    return ret;
   }
 
   public String toString() {

src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLog.java

@@ -164,10 +164,10 @@ public class TestHLog  {
         log.rollWriter();
       }
       log.close();
-      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
+      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+          hbaseDir, logdir, this.oldLogDir, this.fs);
       List<Path> splits =
-        logSplitter.splitLog(hbaseDir, logdir,
-          this.oldLogDir, this.fs, conf);
+        logSplitter.splitLog();
       verifySplits(splits, howmany);
       log = null;
     } finally {

src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLogMethods.java

@@ -24,16 +24,28 @@ import static org.junit.Assert.*;
 import java.io.IOException;
 import java.util.NavigableSet;
 
+import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.KeyValueTestUtil;
+import org.apache.hadoop.hbase.MultithreadedTestUtil;
+import org.apache.hadoop.hbase.MultithreadedTestUtil.TestContext;
+import org.apache.hadoop.hbase.MultithreadedTestUtil.TestThread;
+import org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.EntryBuffers;
+import org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.RegionEntryBuffer;
+import org.apache.hadoop.hbase.util.Bytes;
 import org.junit.Test;
+import static org.mockito.Mockito.mock;
 
 /**
  * Simple testing of a few HLog methods.
  */
 public class TestHLogMethods {
+  private static final byte[] TEST_REGION = Bytes.toBytes("test_region");;
+  private static final byte[] TEST_TABLE = Bytes.toBytes("test_table");
+  
   private final HBaseTestingUtility util = new HBaseTestingUtility();
 
   /**
@@ -84,4 +96,71 @@ public class TestHLogMethods {
     FSDataOutputStream fdos = fs.create(new Path(testdir, name), true);
     fdos.close();
   }
-}
+
+  @Test
+  public void testRegionEntryBuffer() throws Exception {
+    HLogSplitter.RegionEntryBuffer reb = new HLogSplitter.RegionEntryBuffer(
+        TEST_TABLE, TEST_REGION);
+    assertEquals(0, reb.heapSize());
+
+    reb.appendEntry(createTestLogEntry(1));
+    assertTrue(reb.heapSize() > 0);
+  }
+  
+  @Test
+  public void testEntrySink() throws Exception {
+    Configuration conf = new Configuration();
+    HLogSplitter splitter = HLogSplitter.createLogSplitter(
+        conf, mock(Path.class), mock(Path.class), mock(Path.class),
+        mock(FileSystem.class));
+
+    EntryBuffers sink = splitter.new EntryBuffers(1*1024*1024);
+    for (int i = 0; i < 1000; i++) {
+      HLog.Entry entry = createTestLogEntry(i);
+      sink.appendEntry(entry);
+    }
+    
+    assertTrue(sink.totalBuffered > 0);
+    long amountInChunk = sink.totalBuffered;
+    // Get a chunk
+    RegionEntryBuffer chunk = sink.getChunkToWrite();
+    assertEquals(chunk.heapSize(), amountInChunk);
+    
+    // Make sure it got marked that a thread is "working on this"
+    assertTrue(sink.isRegionCurrentlyWriting(TEST_REGION));
+
+    // Insert some more entries
+    for (int i = 0; i < 500; i++) {
+      HLog.Entry entry = createTestLogEntry(i);
+      sink.appendEntry(entry);
+    }    
+    // Asking for another chunk shouldn't work since the first one
+    // is still writing
+    assertNull(sink.getChunkToWrite());
+    
+    // If we say we're done writing the first chunk, then we should be able
+    // to get the second
+    sink.doneWriting(chunk);
+    
+    RegionEntryBuffer chunk2 = sink.getChunkToWrite();
+    assertNotNull(chunk2);
+    assertNotSame(chunk, chunk2);
+    long amountInChunk2 = sink.totalBuffered;
+    // The second chunk had fewer rows than the first
+    assertTrue(amountInChunk2 < amountInChunk);
+    
+    sink.doneWriting(chunk2);
+    assertEquals(0, sink.totalBuffered);
+  }
+  
+  private HLog.Entry createTestLogEntry(int i) {
+    long seq = i;
+    long now = i * 1000;
+    
+    WALEdit edit = new WALEdit();
+    edit.add(KeyValueTestUtil.create("row", "fam", "qual", 1234, "val"));
+    HLogKey key = new HLogKey(TEST_REGION, TEST_TABLE, seq, now);
+    HLog.Entry entry = new HLog.Entry(key, edit);
+    return entry;
+  }
+}

src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestHLogSplit.java

@@ -19,16 +19,14 @@
  */
 package org.apache.hadoop.hbase.regionserver.wal;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.*;
 
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 
@@ -39,7 +37,9 @@ import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hbase.regionserver.wal.HLog.Entry;
 import org.apache.hadoop.hbase.regionserver.wal.HLog.Reader;
 import org.apache.hadoop.hbase.HBaseTestingUtility;
 import org.apache.hadoop.hbase.HConstants;
@@ -52,9 +52,16 @@ import org.apache.hadoop.hbase.util.Threads;
 import org.apache.hadoop.ipc.RemoteException;
 import org.junit.After;
 import org.junit.AfterClass;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
+import org.mockito.Mockito;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
 
 /**
  * Testing {@link HLog} splitting code.
@@ -119,11 +126,15 @@ public class TestHLogSplit {
 
   @Before
   public void setUp() throws Exception {
+    flushToConsole("Cleaning up cluster for new test\n"
+        + "--------------------------");
     conf = TEST_UTIL.getConfiguration();
     fs = TEST_UTIL.getDFSCluster().getFileSystem();
     FileStatus[] entries = fs.listStatus(new Path("/"));
+    flushToConsole("Num entries in /:" + entries.length);
     for (FileStatus dir : entries){
-      fs.delete(dir.getPath(), true);
+      assertTrue("Deleting " + dir.getPath(),
+          fs.delete(dir.getPath(), true));
     }
     seq = 0;
     regions = new ArrayList<String>();
@@ -161,18 +172,23 @@ public class TestHLogSplit {
   public void testSplitFailsIfNewHLogGetsCreatedAfterSplitStarted()
   throws IOException {
     AtomicBoolean stop = new AtomicBoolean(false);
+    
+    FileStatus[] stats = fs.listStatus(new Path("/hbase/t1"));
+    assertTrue("Previous test should clean up table dir",
+        stats == null || stats.length == 0);
+
     generateHLogs(-1);
-    fs.initialize(fs.getUri(), conf);
+    
     try {
     (new ZombieNewLogWriterRegionServer(stop)).start();
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-      logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     } finally {
       stop.set(true);
     }
   }
 
-
   @Test
   public void testSplitPreservesEdits() throws IOException{
     final String REGION = "region__1";
@@ -181,8 +197,9 @@ public class TestHLogSplit {
 
     generateHLogs(1, 10, -1);
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+      hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     Path originalLog = (fs.listStatus(oldLogDir))[0].getPath();
     Path splitLog = getLogForRegion(hbaseDir, TABLE_NAME, REGION);
@@ -202,8 +219,9 @@ public class TestHLogSplit {
     // initialize will create a new DFSClient with a new client ID
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
 
     for (String region : regions) {
@@ -224,8 +242,9 @@ public class TestHLogSplit {
     // initialize will create a new DFSClient with a new client ID
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
@@ -240,8 +259,9 @@ public class TestHLogSplit {
 
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
@@ -260,8 +280,9 @@ public class TestHLogSplit {
             Corruptions.APPEND_GARBAGE, true, fs);
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
       assertEquals(NUM_WRITERS * ENTRIES, countHLog(logfile, fs, conf));
@@ -278,8 +299,9 @@ public class TestHLogSplit {
             Corruptions.INSERT_GARBAGE_ON_FIRST_LINE, true, fs);
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
       assertEquals((NUM_WRITERS - 1) * ENTRIES, countHLog(logfile, fs, conf));
@@ -296,8 +318,9 @@ public class TestHLogSplit {
     corruptHLog(new Path(hlogDir, HLOG_FILE_PREFIX + "5"),
             Corruptions.INSERT_GARBAGE_IN_THE_MIDDLE, false, fs);
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
@@ -323,13 +346,13 @@ public class TestHLogSplit {
     Path c1 = new Path(hlogDir, HLOG_FILE_PREFIX + "0");
       conf.setClass("hbase.regionserver.hlog.reader.impl",
           FaultySequenceFileLogReader.class, HLog.Reader.class);
-      String[] failureTypes = { "begin", "middle", "end" };
       for (FaultySequenceFileLogReader.FailureType  failureType : FaultySequenceFileLogReader.FailureType.values()) {
         conf.set("faultysequencefilelogreader.failuretype", failureType.name());
         generateHLogs(1, ENTRIES, -1);
         fs.initialize(fs.getUri(), conf);
-        HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-        logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+        HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+            hbaseDir, hlogDir, oldLogDir, fs);
+        logSplitter.splitLog();
         FileStatus[] archivedLogs = fs.listStatus(corruptDir);
         assertEquals("expected a different file", c1.getName(), archivedLogs[0]
             .getPath().getName());
@@ -358,8 +381,9 @@ public class TestHLogSplit {
       conf.set("faultysequencefilelogreader.failuretype", FaultySequenceFileLogReader.FailureType.BEGINNING.name());
       generateHLogs(Integer.MAX_VALUE);
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     } finally {
       conf.setClass("hbase.regionserver.hlog.reader.impl", backupClass,
           Reader.class);
@@ -383,9 +407,10 @@ public class TestHLogSplit {
       conf.set("faultysequencefilelogreader.failuretype", FaultySequenceFileLogReader.FailureType.BEGINNING.name());
       generateHLogs(-1);
       fs.initialize(fs.getUri(), conf);
-      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
+      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+          hbaseDir, hlogDir, oldLogDir, fs);
       try {
-        logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+        logSplitter.splitLog();
       } catch (IOException e) {
         assertEquals(
             "if skip.errors is false all files should remain in place",
@@ -413,8 +438,9 @@ public class TestHLogSplit {
     corruptHLog(c1, Corruptions.TRUNCATE, true, fs);
 
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     Path originalLog = (fs.listStatus(oldLogDir))[0].getPath();
     Path splitLog = getLogForRegion(hbaseDir, TABLE_NAME, REGION);
@@ -437,8 +463,9 @@ public class TestHLogSplit {
     generateHLogs(-1);
 
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     FileStatus[] archivedLogs = fs.listStatus(oldLogDir);
 
@@ -449,8 +476,9 @@ public class TestHLogSplit {
   public void testSplit() throws IOException {
     generateHLogs(-1);
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     for (String region : regions) {
       Path logfile = getLogForRegion(hbaseDir, TABLE_NAME, region);
@@ -464,12 +492,16 @@ public class TestHLogSplit {
   throws IOException {
     generateHLogs(-1);
     fs.initialize(fs.getUri(), conf);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     FileStatus [] statuses = null;
     try {
       statuses = fs.listStatus(hlogDir);
-      assertNull(statuses);
+      if (statuses != null) {
+        Assert.fail("Files left in log dir: " +
+            Joiner.on(",").join(FileUtil.stat2Paths(statuses)));
+      }
     } catch (FileNotFoundException e) {
       // hadoop 0.21 throws FNFE whereas hadoop 0.20 returns null
     }
@@ -516,8 +548,9 @@ public class TestHLogSplit {
     try {
       zombie.start();
       try {
-        HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-        logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+        HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+            hbaseDir, hlogDir, oldLogDir, fs);
+        logSplitter.splitLog();
       } catch (IOException ex) {/* expected */}
       int logFilesNumber = fs.listStatus(hlogDir).length;
 
@@ -549,11 +582,12 @@ public class TestHLogSplit {
 
     try {
       InstrumentedSequenceFileLogWriter.activateFailure = true;
-      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-      logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+      HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+          hbaseDir, hlogDir, oldLogDir, fs);
+      logSplitter.splitLog();
 
     } catch (IOException e) {
-      assertEquals("java.io.IOException: This exception is instrumented and should only be thrown for testing", e.getMessage());
+      assertEquals("This exception is instrumented and should only be thrown for testing", e.getMessage());
       throw e;
     } finally {
       InstrumentedSequenceFileLogWriter.activateFailure = false;
@@ -561,7 +595,10 @@ public class TestHLogSplit {
   }
 
 
-//  @Test
+  // @Test TODO this test has been disabled since it was created!
+  // It currently fails because the second split doesn't output anything
+  // -- because there are no region dirs after we move aside the first
+  // split result
   public void testSplittingLargeNumberOfRegionsConsistency() throws IOException {
 
     regions.removeAll(regions);
@@ -572,8 +609,9 @@ public class TestHLogSplit {
     generateHLogs(1, 100, -1);
     fs.initialize(fs.getUri(), conf);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     fs.rename(oldLogDir, hlogDir);
     Path firstSplitPath = new Path(hbaseDir, Bytes.toString(TABLE_NAME) + ".first");
     Path splitPath = new Path(hbaseDir, Bytes.toString(TABLE_NAME));
@@ -582,7 +620,9 @@ public class TestHLogSplit {
 
 
     fs.initialize(fs.getUri(), conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
 
     assertEquals(0, compareHLogSplitDirs(firstSplitPath, splitPath));
   }
@@ -600,11 +640,161 @@ public class TestHLogSplit {
     Path regiondir = new Path(tabledir, region);
     fs.delete(regiondir, true);
 
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf);
-    logSplitter.splitLog(hbaseDir, hlogDir, oldLogDir, fs, conf);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(conf,
+        hbaseDir, hlogDir, oldLogDir, fs);
+    logSplitter.splitLog();
     
     assertFalse(fs.exists(regiondir));
   }
+  
+  @Test
+  public void testIOEOnOutputThread() throws Exception {
+    conf.setBoolean(HBASE_SKIP_ERRORS, false);
+
+    generateHLogs(-1);
+
+    fs.initialize(fs.getUri(), conf);
+    // Set up a splitter that will throw an IOE on the output side
+    HLogSplitter logSplitter = new HLogSplitter(
+        conf, hbaseDir, hlogDir, oldLogDir, fs) {
+      protected HLog.Writer createWriter(FileSystem fs, Path logfile, Configuration conf)
+      throws IOException {
+        HLog.Writer mockWriter = Mockito.mock(HLog.Writer.class);
+        Mockito.doThrow(new IOException("Injected")).when(mockWriter).append(Mockito.<HLog.Entry>any());
+        return mockWriter;
+        
+      }
+    };
+    try {
+      logSplitter.splitLog();
+      fail("Didn't throw!");
+    } catch (IOException ioe) {
+      assertTrue(ioe.toString().contains("Injected"));
+    }
+  }
+  
+  /**
+   * Test log split process with fake data and lots of edits to trigger threading
+   * issues.
+   */
+  @Test
+  public void testThreading() throws Exception {
+    doTestThreading(20000, 128*1024*1024, 0);
+  }
+  
+  /**
+   * Test blocking behavior of the log split process if writers are writing slower
+   * than the reader is reading.
+   */
+  @Test
+  public void testThreadingSlowWriterSmallBuffer() throws Exception {
+    doTestThreading(200, 1024, 50);
+  }
+  
+  /**
+   * Sets up a log splitter with a mock reader and writer. The mock reader generates
+   * a specified number of edits spread across 5 regions. The mock writer optionally
+   * sleeps for each edit it is fed.
+   * *
+   * After the split is complete, verifies that the statistics show the correct number
+   * of edits output into each region.
+   * 
+   * @param numFakeEdits number of fake edits to push through pipeline
+   * @param bufferSize size of in-memory buffer
+   * @param writerSlowness writer threads will sleep this many ms per edit
+   */
+  private void doTestThreading(final int numFakeEdits,
+      final int bufferSize,
+      final int writerSlowness) throws Exception {
+
+    Configuration localConf = new Configuration(conf);
+    localConf.setInt("hbase.regionserver.hlog.splitlog.buffersize", bufferSize);
+
+    // Create a fake log file (we'll override the reader to produce a stream of edits)
+    FSDataOutputStream out = fs.create(new Path(hlogDir, HLOG_FILE_PREFIX + ".fake"));
+    out.close();
+
+    // Make region dirs for our destination regions so the output doesn't get skipped
+    final List<String> regions = ImmutableList.of("r0", "r1", "r2", "r3", "r4"); 
+    makeRegionDirs(fs, regions);
+
+    // Create a splitter that reads and writes the data without touching disk
+    HLogSplitter logSplitter = new HLogSplitter(
+        localConf, hbaseDir, hlogDir, oldLogDir, fs) {
+      
+      /* Produce a mock writer that doesn't write anywhere */
+      protected HLog.Writer createWriter(FileSystem fs, Path logfile, Configuration conf)
+      throws IOException {
+        HLog.Writer mockWriter = Mockito.mock(HLog.Writer.class);
+        Mockito.doAnswer(new Answer<Void>() {
+          int expectedIndex = 0;
+          
+          @Override
+          public Void answer(InvocationOnMock invocation) {
+            if (writerSlowness > 0) {
+              try {
+                Thread.sleep(writerSlowness);
+              } catch (InterruptedException ie) {
+                Thread.currentThread().interrupt();
+              }
+            }
+            HLog.Entry entry = (Entry) invocation.getArguments()[0];
+            WALEdit edit = entry.getEdit();
+            List<KeyValue> keyValues = edit.getKeyValues();
+            assertEquals(1, keyValues.size());
+            KeyValue kv = keyValues.get(0);
+            
+            // Check that the edits come in the right order.
+            assertEquals(expectedIndex, Bytes.toInt(kv.getRow()));
+            expectedIndex++;
+            return null;
+          }
+        }).when(mockWriter).append(Mockito.<HLog.Entry>any());
+        return mockWriter;        
+      }
+      
+      
+      /* Produce a mock reader that generates fake entries */
+      protected Reader getReader(FileSystem fs, Path curLogFile, Configuration conf)
+      throws IOException {
+        Reader mockReader = Mockito.mock(Reader.class);
+        Mockito.doAnswer(new Answer<HLog.Entry>() {
+          int index = 0;
+
+          @Override
+          public HLog.Entry answer(InvocationOnMock invocation) throws Throwable {
+            if (index >= numFakeEdits) return null;
+           
+            // Generate r0 through r4 in round robin fashion
+            int regionIdx = index % regions.size();
+            byte region[] = new byte[] {(byte)'r', (byte) (0x30 + regionIdx)};
+            
+            HLog.Entry ret = createTestEntry(TABLE_NAME, region,
+                Bytes.toBytes((int)(index / regions.size())),
+                FAMILY, QUALIFIER, VALUE, index);
+            index++;
+            return ret;
+          }
+        }).when(mockReader).next();
+        return mockReader;
+      }
+    };
+    
+    logSplitter.splitLog();
+    
+    // Verify number of written edits per region
+
+    Map<byte[], Long> outputCounts = logSplitter.getOutputCounts();
+    for (Map.Entry<byte[], Long> entry : outputCounts.entrySet()) {
+      LOG.info("Got " + entry.getValue() + " output edits for region " + 
+          Bytes.toString(entry.getKey()));
+      
+      assertEquals((long)entry.getValue(), numFakeEdits / regions.size());
+    }
+    assertEquals(regions.size(), outputCounts.size());
+  }
+  
+  
 
   /**
    * This thread will keep writing to the file after the split process has started
@@ -677,29 +867,19 @@ public class TestHLogSplit {
       if (stop.get()) {
         return;
       }
-      boolean splitStarted = false;
-      Path p = new Path(hbaseDir, new String(TABLE_NAME));
-      while (!splitStarted) {
-        try {
-          FileStatus [] statuses = fs.listStatus(p);
-          // In 0.20, listStatus comes back with a null if file doesn't exit.
-          // In 0.21, it throws FNFE.
-          if (statuses != null && statuses.length > 0) {
-            // Done.
-            break;
-          }
-        } catch (FileNotFoundException e) {
-          // Expected in hadoop 0.21
-        } catch (IOException e1) {
-          assertTrue("Failed to list status ", false);
-        }
-        flushToConsole("Juliet: split not started, sleeping a bit...");
-        Threads.sleep(100);
-      }
+      Path tableDir = new Path(hbaseDir, new String(TABLE_NAME));
+      Path regionDir = new Path(tableDir, regions.get(0));      
+      Path recoveredEdits = new Path(regionDir, HLogSplitter.RECOVERED_EDITS);
       String region = "juliet";
       Path julietLog = new Path(hlogDir, HLOG_FILE_PREFIX + ".juliet");
       try {
-        fs.mkdirs(new Path(new Path(hbaseDir, region), region));
+
+        while (!fs.exists(recoveredEdits) && !stop.get()) {
+          flushToConsole("Juliet: split not started, sleeping a bit...");
+          Threads.sleep(10);
+        }
+
+        fs.mkdirs(new Path(tableDir, region));
         HLog.Writer writer = HLog.createWriter(fs,
                 julietLog, conf);
         appendEntry(writer, "juliet".getBytes(), ("juliet").getBytes(),
@@ -722,10 +902,15 @@ public class TestHLogSplit {
     generateHLogs(NUM_WRITERS, ENTRIES, leaveOpen);
   }
 
-  private void generateHLogs(int writers, int entries, int leaveOpen) throws IOException {
+  private void makeRegionDirs(FileSystem fs, List<String> regions) throws IOException {
     for (String region : regions) {
+      flushToConsole("Creating dir for region " + region);
       fs.mkdirs(new Path(tabledir, region));
     }
+  }
+  
+  private void generateHLogs(int writers, int entries, int leaveOpen) throws IOException {
+    makeRegionDirs(fs, regions);
     for (int i = 0; i < writers; i++) {
       writer[i] = HLog.createWriter(fs, new Path(hlogDir, HLOG_FILE_PREFIX + i), conf);
       for (int j = 0; j < entries; j++) {
@@ -835,14 +1020,20 @@ public class TestHLogSplit {
                           byte[] value, long seq)
           throws IOException {
 
+    writer.append(createTestEntry(table, region, row, family, qualifier, value, seq));
+    writer.sync();
+    return seq;
+  }
+  
+  private HLog.Entry createTestEntry(
+      byte[] table, byte[] region,
+      byte[] row, byte[] family, byte[] qualifier,
+      byte[] value, long seq) {
     long time = System.nanoTime();
     WALEdit edit = new WALEdit();
     seq++;
     edit.add(new KeyValue(row, family, qualifier, time, KeyValue.Type.Put, value));
-    writer.append(new HLog.Entry(new HLogKey(region, table, seq, time), edit));
-    writer.sync();
-    return seq;
-
+    return new HLog.Entry(new HLogKey(region, table, seq, time), edit);
   }
 
 
@@ -864,6 +1055,14 @@ public class TestHLogSplit {
   private int compareHLogSplitDirs(Path p1, Path p2) throws IOException {
     FileStatus[] f1 = fs.listStatus(p1);
     FileStatus[] f2 = fs.listStatus(p2);
+    assertNotNull("Path " + p1 + " doesn't exist", f1);
+    assertNotNull("Path " + p2 + " doesn't exist", f2);
+    
+    System.out.println("Files in " + p1 + ": " +
+        Joiner.on(",").join(FileUtil.stat2Paths(f1)));
+    System.out.println("Files in " + p2 + ": " +
+        Joiner.on(",").join(FileUtil.stat2Paths(f2)));
+    assertEquals(f1.length, f2.length);
 
     for (int i = 0; i < f1.length; i++) {
       // Regions now have a directory named RECOVERED_EDITS_DIR and in here

src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestWALReplay.java

@@ -487,9 +487,9 @@ public class TestWALReplay {
    */
   private Path runWALSplit(final Configuration c) throws IOException {
     FileSystem fs = FileSystem.get(c);
-    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(c);
-    List<Path> splits = logSplitter.splitLog(this.hbaseRootDir, this.logDir,
-      this.oldLogDir, fs, c);
+    HLogSplitter logSplitter = HLogSplitter.createLogSplitter(c,
+        this.hbaseRootDir, this.logDir, this.oldLogDir, fs);
+    List<Path> splits = logSplitter.splitLog();
     // Split should generate only 1 file since there's only 1 region
     assertEquals(1, splits.size());
     // Make sure the file exists