HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails in the middle (kihwal via daryn)
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1452384 13f79535-47bb-0310-9956-ffa450edef68
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@ -2317,6 +2317,9 @@ Release 0.23.7 - UNRELEASED
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HDFS-4495. Allow client-side lease renewal to be retried beyond soft-limit
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(kihwal)
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HDFS-4128. 2NN gets stuck in inconsistent state if edit log replay fails
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in the middle (kihwal via daryn)
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Release 0.23.6 - UNRELEASED
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INCOMPATIBLE CHANGES
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@ -121,6 +121,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
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public static final long DFS_NAMENODE_CHECKPOINT_PERIOD_DEFAULT = 3600;
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public static final String DFS_NAMENODE_CHECKPOINT_TXNS_KEY = "dfs.namenode.checkpoint.txns";
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public static final long DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT = 40000;
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public static final String DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY = "dfs.namenode.checkpoint.max-retries";
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public static final int DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_DEFAULT = 3;
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public static final String DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY = "dfs.namenode.heartbeat.recheck-interval";
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public static final int DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_DEFAULT = 5*60*1000;
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public static final String DFS_NAMENODE_TOLERATE_HEARTBEAT_MULTIPLIER_KEY = "dfs.namenode.tolerate.heartbeat.multiplier";
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@ -39,6 +39,8 @@ public class CheckpointConf {
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/** checkpoint once every this many transactions, regardless of time */
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private final long checkpointTxnCount;
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/** maxium number of retries when merge errors occur */
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private final int maxRetriesOnMergeError;
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public CheckpointConf(Configuration conf) {
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checkpointCheckPeriod = conf.getLong(
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@ -49,6 +51,8 @@ public CheckpointConf(Configuration conf) {
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DFS_NAMENODE_CHECKPOINT_PERIOD_DEFAULT);
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checkpointTxnCount = conf.getLong(DFS_NAMENODE_CHECKPOINT_TXNS_KEY,
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DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT);
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maxRetriesOnMergeError = conf.getInt(DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY,
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DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_DEFAULT);
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warnForDeprecatedConfigs(conf);
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}
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@ -75,4 +79,8 @@ public long getCheckPeriod() {
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public long getTxnCount() {
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return checkpointTxnCount;
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}
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public int getMaxRetriesOnMergeError() {
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return maxRetriesOnMergeError;
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}
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}
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@ -33,6 +33,7 @@ static CheckpointFaultInjector getInstance() {
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public void beforeGetImageSetsHeaders() throws IOException {}
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public void afterSecondaryCallsRollEditLog() throws IOException {}
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public void duringMerge() throws IOException {}
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public void afterSecondaryUploadsNewImage() throws IOException {}
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public void aboutToSendFile(File localfile) throws IOException {}
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@ -144,6 +144,11 @@ FSImage getFSImage() {
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return checkpointImage;
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}
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@VisibleForTesting
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int getMergeErrorCount() {
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return checkpointImage.getMergeErrorCount();
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}
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@VisibleForTesting
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FSNamesystem getFSNamesystem() {
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return namesystem;
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@ -339,6 +344,7 @@ public void doWork() {
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// number of transactions in the edit log that haven't yet been checkpointed.
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//
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long period = checkpointConf.getCheckPeriod();
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int maxRetries = checkpointConf.getMaxRetriesOnMergeError();
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while (shouldRun) {
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try {
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@ -364,6 +370,13 @@ public void doWork() {
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} catch (IOException e) {
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LOG.error("Exception in doCheckpoint", e);
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e.printStackTrace();
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// Prevent a huge number of edits from being created due to
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// unrecoverable conditions and endless retries.
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if (checkpointImage.getMergeErrorCount() > maxRetries) {
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LOG.fatal("Merging failed " +
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checkpointImage.getMergeErrorCount() + " times.");
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terminate(1);
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}
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} catch (Throwable e) {
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LOG.fatal("Throwable Exception in doCheckpoint", e);
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e.printStackTrace();
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@ -498,9 +511,21 @@ boolean doCheckpoint() throws IOException {
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RemoteEditLogManifest manifest =
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namenode.getEditLogManifest(sig.mostRecentCheckpointTxId + 1);
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// Fetch fsimage and edits. Reload the image if previous merge failed.
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loadImage |= downloadCheckpointFiles(
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fsName, checkpointImage, sig, manifest); // Fetch fsimage and edits
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doMerge(sig, manifest, loadImage, checkpointImage, namesystem);
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fsName, checkpointImage, sig, manifest) |
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checkpointImage.hasMergeError();
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try {
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doMerge(sig, manifest, loadImage, checkpointImage, namesystem);
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} catch (IOException ioe) {
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// A merge error occurred. The in-memory file system state may be
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// inconsistent, so the image and edits need to be reloaded.
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checkpointImage.setMergeError();
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throw ioe;
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}
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// Clear any error since merge was successful.
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checkpointImage.clearMergeError();
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//
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// Upload the new image into the NameNode. Then tell the Namenode
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@ -754,6 +779,7 @@ private static CommandLineOpts parseArgs(String[] argv) {
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static class CheckpointStorage extends FSImage {
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private int mergeErrorCount;
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private static class CheckpointLogPurger implements LogsPurgeable {
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private NNStorage storage;
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@ -815,6 +841,7 @@ public void selectInputStreams(Collection<EditLogInputStream> streams,
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// we shouldn't have any editLog instance. Setting to null
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// makes sure we don't accidentally depend on it.
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editLog = null;
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mergeErrorCount = 0;
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// Replace the archival manager with one that can actually work on the
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// 2NN's edits storage.
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@ -881,7 +908,24 @@ void recoverCreate(boolean format) throws IOException {
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}
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}
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}
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boolean hasMergeError() {
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return (mergeErrorCount > 0);
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}
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int getMergeErrorCount() {
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return mergeErrorCount;
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}
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void setMergeError() {
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mergeErrorCount++;
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}
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void clearMergeError() {
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mergeErrorCount = 0;
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}
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/**
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* Ensure that the current/ directory exists in all storage
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* directories
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@ -915,7 +959,9 @@ static void doMerge(
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dstImage.reloadFromImageFile(file, dstNamesystem);
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dstNamesystem.dir.imageLoadComplete();
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}
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// error simulation code for junit test
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CheckpointFaultInjector.getInstance().duringMerge();
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Checkpointer.rollForwardByApplyingLogs(manifest, dstImage, dstNamesystem);
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// The following has the side effect of purging old fsimages/edit logs.
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dstImage.saveFSImageInAllDirs(dstNamesystem, dstImage.getLastAppliedTxId());
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@ -640,6 +640,15 @@
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</description>
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</property>
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<property>
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<name>dfs.namenode.checkpoint.max-retries</name>
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<value>3</value>
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<description>The SecondaryNameNode retries failed checkpointing. If the
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failure occurs while loading fsimage or replaying edits, the number of
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retries is limited by this variable.
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</description>
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</property>
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<property>
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<name>dfs.namenode.num.checkpoints.retained</name>
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<value>2</value>
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@ -74,6 +74,8 @@
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import org.apache.hadoop.test.GenericTestUtils;
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import org.apache.hadoop.test.GenericTestUtils.DelayAnswer;
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import org.apache.hadoop.test.GenericTestUtils.LogCapturer;
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import org.apache.hadoop.util.ExitUtil;
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import org.apache.hadoop.util.ExitUtil.ExitException;
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import org.apache.hadoop.util.StringUtils;
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import org.apache.log4j.Level;
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import org.junit.After;
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@ -226,6 +228,111 @@ public void testWriteTransactionIdHandlesIOE() throws Exception {
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toString().indexOf("storageDirToCheck") != -1);
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}
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/*
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* Simulate exception during edit replay.
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*/
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@Test(timeout=5000)
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public void testReloadOnEditReplayFailure () throws IOException {
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Configuration conf = new HdfsConfiguration();
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FSDataOutputStream fos = null;
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SecondaryNameNode secondary = null;
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MiniDFSCluster cluster = null;
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FileSystem fs = null;
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try {
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cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
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.build();
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cluster.waitActive();
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fs = cluster.getFileSystem();
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secondary = startSecondaryNameNode(conf);
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fos = fs.create(new Path("tmpfile0"));
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fos.write(new byte[] { 0, 1, 2, 3 });
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secondary.doCheckpoint();
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fos.write(new byte[] { 0, 1, 2, 3 });
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fos.hsync();
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// Cause merge to fail in next checkpoint.
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Mockito.doThrow(new IOException(
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"Injecting failure during merge"))
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.when(faultInjector).duringMerge();
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try {
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secondary.doCheckpoint();
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fail("Fault injection failed.");
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} catch (IOException ioe) {
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// This is expected.
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}
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Mockito.reset(faultInjector);
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// The error must be recorded, so next checkpoint will reload image.
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fos.write(new byte[] { 0, 1, 2, 3 });
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fos.hsync();
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assertTrue("Another checkpoint should have reloaded image",
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secondary.doCheckpoint());
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} finally {
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if (secondary != null) {
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secondary.shutdown();
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}
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if (fs != null) {
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fs.close();
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}
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if (cluster != null) {
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cluster.shutdown();
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}
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Mockito.reset(faultInjector);
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}
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}
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/*
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* Simulate 2NN exit due to too many merge failures.
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*/
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@Test(timeout=10000)
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public void testTooManyEditReplayFailures() throws IOException {
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Configuration conf = new HdfsConfiguration();
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conf.set(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_MAX_RETRIES_KEY, "1");
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conf.set(DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_CHECK_PERIOD_KEY, "1");
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FSDataOutputStream fos = null;
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SecondaryNameNode secondary = null;
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MiniDFSCluster cluster = null;
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FileSystem fs = null;
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try {
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cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDatanodes)
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.checkExitOnShutdown(false).build();
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cluster.waitActive();
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fs = cluster.getFileSystem();
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fos = fs.create(new Path("tmpfile0"));
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fos.write(new byte[] { 0, 1, 2, 3 });
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// Cause merge to fail in next checkpoint.
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Mockito.doThrow(new IOException(
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"Injecting failure during merge"))
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.when(faultInjector).duringMerge();
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secondary = startSecondaryNameNode(conf);
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secondary.doWork();
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// Fail if we get here.
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fail("2NN did not exit.");
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} catch (ExitException ee) {
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// ignore
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ExitUtil.resetFirstExitException();
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assertEquals("Max retries", 1, secondary.getMergeErrorCount() - 1);
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} finally {
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if (secondary != null) {
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secondary.shutdown();
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}
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if (fs != null) {
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fs.close();
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}
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if (cluster != null) {
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cluster.shutdown();
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}
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Mockito.reset(faultInjector);
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}
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}
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/*
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* Simulate namenode crashing after rolling edit log.
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*/
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