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HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails in the middle (kihwal via daryn)

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git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1452384 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Daryn Sharp 2013-03-04 16:44:23 +00:00
parent ec13f1eb3a
commit cfa86e6110
7 changed files with 180 additions and 4 deletions
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3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -2317,6 +2317,9 @@ Release 0.23.7 - UNRELEASED
HDFS-4495. Allow client-side lease renewal to be retried beyond soft-limit
(kihwal)
HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails
in the middle (kihwal via daryn)
Release 0.23.6 - UNRELEASED
INCOMPATIBLE CHANGES

2
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
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@ -121,6 +121,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
public static final long DFS_NAMENODE_CHECKPOINT_PERIOD_DEFAULT = 3600;
public static final String DFS_NAMENODE_CHECKPOINT_TXNS_KEY = "dfs.namenode.checkpoint.txns";
public static final long DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT = 40000;
public static final String DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY = "dfs.namenode.checkpoint.max-retries";
public static final int DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_DEFAULT = 3;
public static final String DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY = "dfs.namenode.heartbeat.recheck-interval";
public static final int DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_DEFAULT = 5*60*1000;
public static final String DFS_NAMENODE_TOLERATE_HEARTBEAT_MULTIPLIER_KEY = "dfs.namenode.tolerate.heartbeat.multiplier";

8
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CheckpointConf.java
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@ -39,6 +39,8 @@ public class CheckpointConf {
/** checkpoint once every this many transactions, regardless of time */
private final long checkpointTxnCount;
/** maxium number of retries when merge errors occur */
private final int maxRetriesOnMergeError;
public CheckpointConf(Configuration conf) {
checkpointCheckPeriod = conf.getLong(
@ -49,6 +51,8 @@ public CheckpointConf(Configuration conf) {
DFS_NAMENODE_CHECKPOINT_PERIOD_DEFAULT);
checkpointTxnCount = conf.getLong(DFS_NAMENODE_CHECKPOINT_TXNS_KEY,
DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT);
maxRetriesOnMergeError = conf.getInt(DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY,
DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_DEFAULT);
warnForDeprecatedConfigs(conf);
}
@ -75,4 +79,8 @@ public long getCheckPeriod() {
public long getTxnCount() {
return checkpointTxnCount;
}
public int getMaxRetriesOnMergeError() {
return maxRetriesOnMergeError;
}
}

1
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CheckpointFaultInjector.java
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@ -33,6 +33,7 @@ static CheckpointFaultInjector getInstance() {
public void beforeGetImageSetsHeaders() throws IOException {}
public void afterSecondaryCallsRollEditLog() throws IOException {}
public void duringMerge() throws IOException {}
public void afterSecondaryUploadsNewImage() throws IOException {}
public void aboutToSendFile(File localfile) throws IOException {}

48
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java
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@ -144,6 +144,11 @@ FSImage getFSImage() {
return checkpointImage;
}
@VisibleForTesting
int getMergeErrorCount() {
return checkpointImage.getMergeErrorCount();
}
@VisibleForTesting
FSNamesystem getFSNamesystem() {
return namesystem;
@ -339,6 +344,7 @@ public void doWork() {
// number of transactions in the edit log that haven't yet been checkpointed.
//
long period = checkpointConf.getCheckPeriod();
int maxRetries = checkpointConf.getMaxRetriesOnMergeError();
while (shouldRun) {
try {
@ -364,6 +370,13 @@ public void doWork() {
} catch (IOException e) {
LOG.error("Exception in doCheckpoint", e);
e.printStackTrace();
// Prevent a huge number of edits from being created due to
// unrecoverable conditions and endless retries.
if (checkpointImage.getMergeErrorCount() > maxRetries) {
LOG.fatal("Merging failed " +
checkpointImage.getMergeErrorCount() + " times.");
terminate(1);
}
} catch (Throwable e) {
LOG.fatal("Throwable Exception in doCheckpoint", e);
e.printStackTrace();
@ -498,9 +511,21 @@ boolean doCheckpoint() throws IOException {
RemoteEditLogManifest manifest =
namenode.getEditLogManifest(sig.mostRecentCheckpointTxId + 1);
// Fetch fsimage and edits. Reload the image if previous merge failed.
loadImage |= downloadCheckpointFiles(
fsName, checkpointImage, sig, manifest); // Fetch fsimage and edits
fsName, checkpointImage, sig, manifest) |
checkpointImage.hasMergeError();
try {
doMerge(sig, manifest, loadImage, checkpointImage, namesystem);
} catch (IOException ioe) {
// A merge error occurred. The in-memory file system state may be
// inconsistent, so the image and edits need to be reloaded.
checkpointImage.setMergeError();
throw ioe;
}
// Clear any error since merge was successful.
checkpointImage.clearMergeError();
//
// Upload the new image into the NameNode. Then tell the Namenode
@ -754,6 +779,7 @@ private static CommandLineOpts parseArgs(String[] argv) {
static class CheckpointStorage extends FSImage {
private int mergeErrorCount;
private static class CheckpointLogPurger implements LogsPurgeable {
private NNStorage storage;
@ -815,6 +841,7 @@ public void selectInputStreams(Collection<EditLogInputStream> streams,
// we shouldn't have any editLog instance. Setting to null
// makes sure we don't accidentally depend on it.
editLog = null;
mergeErrorCount = 0;
// Replace the archival manager with one that can actually work on the
// 2NN's edits storage.
@ -882,6 +909,23 @@ void recoverCreate(boolean format) throws IOException {
}
}
boolean hasMergeError() {
return (mergeErrorCount > 0);
}
int getMergeErrorCount() {
return mergeErrorCount;
}
void setMergeError() {
mergeErrorCount++;
}
void clearMergeError() {
mergeErrorCount = 0;
}
/**
* Ensure that the current/ directory exists in all storage
* directories
@ -915,6 +959,8 @@ static void doMerge(
dstImage.reloadFromImageFile(file, dstNamesystem);
dstNamesystem.dir.imageLoadComplete();
}
// error simulation code for junit test
CheckpointFaultInjector.getInstance().duringMerge();
Checkpointer.rollForwardByApplyingLogs(manifest, dstImage, dstNamesystem);
// The following has the side effect of purging old fsimages/edit logs.

9
hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
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@ -640,6 +640,15 @@
</description>
</property>
<property>
<name>dfs.namenode.checkpoint.max-retries</name>
<value>3</value>
<description>The SecondaryNameNode retries failed checkpointing. If the
failure occurs while loading fsimage or replaying edits, the number of
retries is limited by this variable.
</description>
</property>
<property>
<name>dfs.namenode.num.checkpoints.retained</name>
<value>2</value>

107
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
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@ -74,6 +74,8 @@
import org.apache.hadoop.test.GenericTestUtils;
import org.apache.hadoop.test.GenericTestUtils.DelayAnswer;
import org.apache.hadoop.test.GenericTestUtils.LogCapturer;
import org.apache.hadoop.util.ExitUtil;
import org.apache.hadoop.util.ExitUtil.ExitException;
import org.apache.hadoop.util.StringUtils;
import org.apache.log4j.Level;
import org.junit.After;
@ -226,6 +228,111 @@ public void testWriteTransactionIdHandlesIOE() throws Exception {
toString().indexOf("storageDirToCheck") != -1);
}
/*
* Simulate exception during edit replay.
*/
@Test(timeout=5000)
public void testReloadOnEditReplayFailure () throws IOException {
Configuration conf = new HdfsConfiguration();
FSDataOutputStream fos = null;
SecondaryNameNode secondary = null;
MiniDFSCluster cluster = null;
FileSystem fs = null;
try {
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
.build();
cluster.waitActive();
fs = cluster.getFileSystem();
secondary = startSecondaryNameNode(conf);
fos = fs.create(new Path("tmpfile0"));
fos.write(new byte[] { 0, 1, 2, 3 });
secondary.doCheckpoint();
fos.write(new byte[] { 0, 1, 2, 3 });
fos.hsync();
// Cause merge to fail in next checkpoint.
Mockito.doThrow(new IOException(
"Injecting failure during merge"))
.when(faultInjector).duringMerge();
try {
secondary.doCheckpoint();
fail("Fault injection failed.");
} catch (IOException ioe) {
// This is expected.
}
Mockito.reset(faultInjector);
// The error must be recorded, so next checkpoint will reload image.
fos.write(new byte[] { 0, 1, 2, 3 });
fos.hsync();
assertTrue("Another checkpoint should have reloaded image",
secondary.doCheckpoint());
} finally {
if (secondary != null) {
secondary.shutdown();
}
if (fs != null) {
fs.close();
}
if (cluster != null) {
cluster.shutdown();
}
Mockito.reset(faultInjector);
}
}
/*
* Simulate 2NN exit due to too many merge failures.
*/
@Test(timeout=10000)
public void testTooManyEditReplayFailures() throws IOException {
Configuration conf = new HdfsConfiguration();
conf.set(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY, "1");
conf.set(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_CHECK_PERIOD_KEY, "1");
FSDataOutputStream fos = null;
SecondaryNameNode secondary = null;
MiniDFSCluster cluster = null;
FileSystem fs = null;
try {
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
.checkExitOnShutdown(false).build();
cluster.waitActive();
fs = cluster.getFileSystem();
fos = fs.create(new Path("tmpfile0"));
fos.write(new byte[] { 0, 1, 2, 3 });
// Cause merge to fail in next checkpoint.
Mockito.doThrow(new IOException(
"Injecting failure during merge"))
.when(faultInjector).duringMerge();
secondary = startSecondaryNameNode(conf);
secondary.doWork();
// Fail if we get here.
fail("2NN did not exit.");
} catch (ExitException ee) {
// ignore
ExitUtil.resetFirstExitException();
assertEquals("Max retries", 1, secondary.getMergeErrorCount() - 1);
} finally {
if (secondary != null) {
secondary.shutdown();
}
if (fs != null) {
fs.close();
}
if (cluster != null) {
cluster.shutdown();
}
Mockito.reset(faultInjector);
}
}
/*
* Simulate namenode crashing after rolling edit log.
*/