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https://issues.apache.org/jira/browse/HDFS-11292?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yongjun Zhang updated HDFS-11292:
---------------------------------
Attachment: HDFS-11292.002.patch
> log lastWrittenTxId in logSyncAll
> ---------------------------------
>
> Key: HDFS-11292
> URL: https://issues.apache.org/jira/browse/HDFS-11292
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-11292.001.patch, HDFS-11292.002.patch
>
>
> For the issue reported in HDFS-10943, even after HDFS-7964's fix is included,
> the problem still exists, this means there might be some synchronization
> issue.
> To diagnose that, create this jira to report the lastWrittenTxId info in
> {{logSyncAll()}} call, such that we can compare against the error message
> reported in HDFS-7964
> Specifically, there is two possibility for the HDFS-10943 issue:
> 1. {{logSyncAll()}} (statement A in the code quoted below) doesn't flush all
> requested txs for some reason
> 2. {{logSyncAll()}} does flush all requested txs, but some new txs sneaked
> in between A and B. It's observed that the lastWrittenTxId in B and C are the
> same.
> This proposed reporting would help confirming if 2 is true.
> {code}
> public synchronized void endCurrentLogSegment(boolean writeEndTxn) {
> LOG.info("Ending log segment " + curSegmentTxId);
> Preconditions.checkState(isSegmentOpen(),
> "Bad state: %s", state);
> if (writeEndTxn) {
> logEdit(LogSegmentOp.getInstance(cache.get(),
> FSEditLogOpCodes.OP_END_LOG_SEGMENT));
> }
> // always sync to ensure all edits are flushed.
> A. logSyncAll();
> B. printStatistics(true);
> final long lastTxId = getLastWrittenTxId();
> try {
> C. journalSet.finalizeLogSegment(curSegmentTxId, lastTxId);
> editLogStream = null;
> } catch (IOException e) {
> //All journals have failed, it will be handled in logSync.
> }
> state = State.BETWEEN_LOG_SEGMENTS;
> }
> {code}
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