HDFS-11180. Intermittent deadlock in NameNode when failover happens.
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@ -108,6 +108,33 @@
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<Class name="org.apache.hadoop.hdfs.server.namenode.FSEditLog" />
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<Field name="journalSet" />
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<Bug pattern="IS2_INCONSISTENT_SYNC" />
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</Match>
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<!--
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FSEditLog#getTotalSyncCount is not synchronized because this method is
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used by metrics. NullPointerException can happen and it is ignored.
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-->
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<Match>
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<Class name="org.apache.hadoop.hdfs.server.namenode.FSEditLog" />
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<Field name="editLogStream" />
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<Bug pattern="IS2_INCONSISTENT_SYNC" />
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</Match>
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<!--
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FSEditLog#isOpenForWriteWithoutLock and FSEditLog#isSegmentOpenWithoutLock
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are not synchronized because these methods are used by metrics.
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-->
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<Match>
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<Class name="org.apache.hadoop.hdfs.server.namenode.FSEditLog" />
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<Field name="state" />
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<Bug pattern="IS2_INCONSISTENT_SYNC" />
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</Match>
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<!--
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All of the threads which update/increment txid are synchronized,
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so make txid volatile instead of AtomicLong.
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-->
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<Match>
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<Class name="org.apache.hadoop.hdfs.server.namenode.FSEditLog" />
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<Field name="txid" />
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<Bug pattern="VO_VOLATILE_INCREMENT" />
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</Match>
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<!--
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This method isn't performance-critical and is much clearer to write as it's written.
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@ -156,14 +156,16 @@ public class FSEditLog implements LogsPurgeable {
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private EditLogOutputStream editLogStream = null;
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// a monotonically increasing counter that represents transactionIds.
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private long txid = 0;
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// All of the threads which update/increment txid are synchronized,
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// so make txid volatile instead of AtomicLong.
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private volatile long txid = 0;
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// stores the last synced transactionId.
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private long synctxid = 0;
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// the first txid of the log that's currently open for writing.
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// If this value is N, we are currently writing to edits_inprogress_N
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private long curSegmentTxId = HdfsServerConstants.INVALID_TXID;
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private volatile long curSegmentTxId = HdfsServerConstants.INVALID_TXID;
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// the time of printing the statistics to the log file.
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private long lastPrintTime;
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@ -339,7 +341,18 @@ public class FSEditLog implements LogsPurgeable {
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return state == State.IN_SEGMENT ||
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state == State.BETWEEN_LOG_SEGMENTS;
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}
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/**
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* Return true if the log is currently open in write mode.
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* This method is not synchronized and must be used only for metrics.
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* @return true if the log is currently open in write mode, regardless
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* of whether it actually has an open segment.
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*/
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boolean isOpenForWriteWithoutLock() {
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return state == State.IN_SEGMENT ||
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state == State.BETWEEN_LOG_SEGMENTS;
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}
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/**
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* @return true if the log is open in write mode and has a segment open
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* ready to take edits.
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@ -348,6 +361,16 @@ public class FSEditLog implements LogsPurgeable {
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return state == State.IN_SEGMENT;
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}
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/**
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* Return true the state is IN_SEGMENT.
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* This method is not synchronized and must be used only for metrics.
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* @return true if the log is open in write mode and has a segment open
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* ready to take edits.
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*/
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boolean isSegmentOpenWithoutLock() {
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return state == State.IN_SEGMENT;
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}
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/**
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* @return true if the log is open in read mode.
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*/
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@ -523,7 +546,16 @@ public class FSEditLog implements LogsPurgeable {
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public synchronized long getLastWrittenTxId() {
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return txid;
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}
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/**
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* Return the transaction ID of the last transaction written to the log.
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* This method is not synchronized and must be used only for metrics.
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* @return The transaction ID of the last transaction written to the log
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*/
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long getLastWrittenTxIdWithoutLock() {
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return txid;
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}
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/**
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* @return the first transaction ID in the current log segment
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*/
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@ -532,7 +564,16 @@ public class FSEditLog implements LogsPurgeable {
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"Bad state: %s", state);
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return curSegmentTxId;
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}
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/**
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* Return the first transaction ID in the current log segment.
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* This method is not synchronized and must be used only for metrics.
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* @return The first transaction ID in the current log segment
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*/
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long getCurSegmentTxIdWithoutLock() {
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return curSegmentTxId;
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}
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/**
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* Set the transaction ID to use for the next transaction written.
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*/
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@ -1183,7 +1224,9 @@ public class FSEditLog implements LogsPurgeable {
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/**
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* Get all the journals this edit log is currently operating on.
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*/
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synchronized List<JournalAndStream> getJournals() {
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List<JournalAndStream> getJournals() {
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// The list implementation is CopyOnWriteArrayList,
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// so we don't need to synchronize this method.
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return journalSet.getAllJournalStreams();
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}
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@ -1191,7 +1234,7 @@ public class FSEditLog implements LogsPurgeable {
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* Used only by tests.
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*/
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@VisibleForTesting
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synchronized public JournalSet getJournalSet() {
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public JournalSet getJournalSet() {
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return journalSet;
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}
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@ -1677,11 +1720,18 @@ public class FSEditLog implements LogsPurgeable {
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* Return total number of syncs happened on this edit log.
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* @return long - count
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*/
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public synchronized long getTotalSyncCount() {
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if (editLogStream != null) {
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return editLogStream.getNumSync();
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} else {
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public long getTotalSyncCount() {
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// Avoid NPE as possible.
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if (editLogStream == null) {
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return 0;
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}
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long count = 0;
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try {
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count = editLogStream.getNumSync();
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} catch (NullPointerException ignore) {
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// This method is used for metrics, so we don't synchronize it.
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// Therefore NPE can happen even if there is a null check before.
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}
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return count;
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}
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}
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@ -927,7 +927,7 @@ public class FSImage implements Closeable {
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Canceler canceler) throws IOException {
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FSImageCompression compression =
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FSImageCompression.createCompression(conf);
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long txid = getLastAppliedOrWrittenTxId();
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long txid = getCorrectLastAppliedOrWrittenTxId();
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SaveNamespaceContext ctx = new SaveNamespaceContext(source, txid,
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canceler);
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FSImageFormat.Saver saver = new FSImageFormat.Saver(ctx);
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@ -1025,7 +1025,7 @@ public class FSImage implements Closeable {
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if (editLogWasOpen) {
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editLog.endCurrentLogSegment(true);
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}
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long imageTxId = getLastAppliedOrWrittenTxId();
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long imageTxId = getCorrectLastAppliedOrWrittenTxId();
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if (!addToCheckpointing(imageTxId)) {
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throw new IOException(
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"FS image is being downloaded from another NN at txid " + imageTxId);
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@ -1396,6 +1396,15 @@ public class FSImage implements Closeable {
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}
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public long getLastAppliedOrWrittenTxId() {
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return Math.max(lastAppliedTxId,
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editLog != null ? editLog.getLastWrittenTxIdWithoutLock() : 0);
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}
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/**
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* This method holds a lock of FSEditLog to get the correct value.
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* This method must not be used for metrics.
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*/
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public long getCorrectLastAppliedOrWrittenTxId() {
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return Math.max(lastAppliedTxId,
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editLog != null ? editLog.getLastWrittenTxId() : 0);
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}
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@ -3633,7 +3633,7 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
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//create ha status
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final NNHAStatusHeartbeat haState = new NNHAStatusHeartbeat(
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haContext.getState().getServiceState(),
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getFSImage().getLastAppliedOrWrittenTxId());
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getFSImage().getCorrectLastAppliedOrWrittenTxId());
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return new HeartbeatResponse(cmds, haState, rollingUpgradeInfo,
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blockReportLeaseId);
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@ -3758,7 +3758,7 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
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public void run() {
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while (fsRunning && shouldRun) {
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try {
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long numEdits = getTransactionsSinceLastLogRoll();
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long numEdits = getCorrectTransactionsSinceLastLogRoll();
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if (numEdits > rollThreshold) {
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FSNamesystem.LOG.info("NameNode rolling its own edit log because"
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+ " number of edits in open segment exceeds threshold of "
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@ -3907,17 +3907,30 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
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@Metric({"TransactionsSinceLastLogRoll",
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"Number of transactions since last edit log roll"})
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public long getTransactionsSinceLastLogRoll() {
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if (isInStandbyState() || !getEditLog().isSegmentOpenWithoutLock()) {
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return 0;
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} else {
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return getEditLog().getLastWrittenTxIdWithoutLock() -
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getEditLog().getCurSegmentTxIdWithoutLock() + 1;
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}
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}
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/**
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* Get the correct number of transactions since last edit log roll.
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* This method holds a lock of FSEditLog and must not be used for metrics.
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*/
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private long getCorrectTransactionsSinceLastLogRoll() {
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if (isInStandbyState() || !getEditLog().isSegmentOpen()) {
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return 0;
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} else {
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return getEditLog().getLastWrittenTxId() -
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getEditLog().getCurSegmentTxId() + 1;
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getEditLog().getCurSegmentTxId() + 1;
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}
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}
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@Metric({"LastWrittenTransactionId", "Transaction ID written to the edit log"})
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public long getLastWrittenTransactionId() {
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return getEditLog().getLastWrittenTxId();
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return getEditLog().getLastWrittenTxIdWithoutLock();
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}
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@Metric({"LastCheckpointTime",
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@ -5587,7 +5600,9 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
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List<Map<String, String>> jasList = new ArrayList<Map<String, String>>();
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FSEditLog log = getFSImage().getEditLog();
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if (log != null) {
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boolean openForWrite = log.isOpenForWrite();
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// This flag can be false because we cannot hold a lock of FSEditLog
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// for metrics.
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boolean openForWrite = log.isOpenForWriteWithoutLock();
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for (JournalAndStream jas : log.getJournals()) {
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final Map<String, String> jasMap = new HashMap<String, String>();
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String manager = jas.getManager().toString();
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@ -1211,7 +1211,7 @@ public class NameNodeRpcServer implements NamenodeProtocols {
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checkNNStartup();
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namesystem.checkOperation(OperationCategory.UNCHECKED);
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namesystem.checkSuperuserPrivilege();
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return namesystem.getFSImage().getLastAppliedOrWrittenTxId();
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return namesystem.getFSImage().getCorrectLastAppliedOrWrittenTxId();
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}
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@Override // NamenodeProtocol
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@ -165,7 +165,7 @@ public class StandbyCheckpointer {
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FSImage img = namesystem.getFSImage();
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long prevCheckpointTxId = img.getStorage().getMostRecentCheckpointTxId();
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long thisCheckpointTxId = img.getLastAppliedOrWrittenTxId();
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long thisCheckpointTxId = img.getCorrectLastAppliedOrWrittenTxId();
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assert thisCheckpointTxId >= prevCheckpointTxId;
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if (thisCheckpointTxId == prevCheckpointTxId) {
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LOG.info("A checkpoint was triggered but the Standby Node has not " +
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@ -253,7 +253,7 @@ public class StandbyCheckpointer {
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private long countUncheckpointedTxns() {
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FSImage img = namesystem.getFSImage();
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return img.getLastAppliedOrWrittenTxId() -
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return img.getCorrectLastAppliedOrWrittenTxId() -
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img.getStorage().getMostRecentCheckpointTxId();
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}
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}
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}
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// The test makes sure JMX request can be processed even if FSEditLog
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// is synchronized.
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@Test
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public void testWithFSEditLogLock() throws Exception {
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Configuration conf = new Configuration();
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MiniDFSCluster cluster = null;
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try {
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cluster = new MiniDFSCluster.Builder(conf).build();
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cluster.waitActive();
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synchronized (cluster.getNameNode().getFSImage().getEditLog()) {
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MBeanClient client = new MBeanClient();
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client.start();
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client.join(20000);
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assertTrue("JMX calls are blocked when FSEditLog" +
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" is synchronized by another thread", client.succeeded);
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client.interrupt();
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}
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} finally {
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if (cluster != null) {
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cluster.shutdown();
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}
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}
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}
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@Test(timeout = 120000)
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public void testFsEditLogMetrics() throws Exception {
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final Configuration conf = new Configuration();
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