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https://issues.apache.org/jira/browse/HBASE-3674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13009514#comment-13009514
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Nicolas Spiegelberg commented on HBASE-3674:
--------------------------------------------
+1
> Treat ChecksumException as we would a ParseException splitting logs; else we
> replay split on every restart
> ----------------------------------------------------------------------------------------------------------
>
> Key: HBASE-3674
> URL: https://issues.apache.org/jira/browse/HBASE-3674
> Project: HBase
> Issue Type: Bug
> Components: wal
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Fix For: 0.90.2
>
> Attachments: 3674-v2.txt, 3674.txt
>
>
> In short, a ChecksumException will fail log processing for a server so we
> skip out w/o archiving logs. On restart, we'll then reprocess the logs --
> hit the checksumexception anew, usually -- and so on.
> Here is the splitLog method (edited):
> {code}
> private List<Path> splitLog(final FileStatus[] logfiles) throws IOException
> {
> ....
> outputSink.startWriterThreads(entryBuffers);
>
> try {
> int i = 0;
> for (FileStatus log : logfiles) {
> Path logPath = log.getPath();
> long logLength = log.getLen();
> splitSize += logLength;
> LOG.debug("Splitting hlog " + (i++ + 1) + " of " + logfiles.length
> + ": " + logPath + ", length=" + logLength);
> try {
> recoverFileLease(fs, logPath, conf);
> parseHLog(log, entryBuffers, fs, conf);
> processedLogs.add(logPath);
> } catch (EOFException eof) {
> // truncated files are expected if a RS crashes (see HBASE-2643)
> LOG.info("EOF from hlog " + logPath + ". Continuing");
> processedLogs.add(logPath);
> } catch (FileNotFoundException fnfe) {
> // A file may be missing if the region server was able to archive it
> // before shutting down. This means the edits were persisted already
> LOG.info("A log was missing " + logPath +
> ", probably because it was moved by the" +
> " now dead region server. Continuing");
> processedLogs.add(logPath);
> } catch (IOException e) {
> // If the IOE resulted from bad file format,
> // then this problem is idempotent and retrying won't help
> if (e.getCause() instanceof ParseException ||
> e.getCause() instanceof ChecksumException) {
> LOG.warn("ParseException from hlog " + logPath + ". continuing");
> processedLogs.add(logPath);
> } else {
> if (skipErrors) {
> LOG.info("Got while parsing hlog " + logPath +
> ". Marking as corrupted", e);
> corruptedLogs.add(logPath);
> } else {
> throw e;
> }
> }
> }
> }
> if (fs.listStatus(srcDir).length > processedLogs.size()
> + corruptedLogs.size()) {
> throw new OrphanHLogAfterSplitException(
> "Discovered orphan hlog after split. Maybe the "
> + "HRegionServer was not dead when we started");
> }
> archiveLogs(srcDir, corruptedLogs, processedLogs, oldLogDir, fs, conf);
>
> } finally {
> splits = outputSink.finishWritingAndClose();
> }
> return splits;
> }
> {code}
> Notice how we'll only archive logs only if we successfully split all logs.
> We won't archive 31 of 35 files if we happen to get a checksum exception on
> file 32.
> I think we should treat a ChecksumException the same as a ParseException; a
> retry will not fix it if HDFS could not get around the ChecksumException
> (seems like in our case all replicas were corrupt).
> Here is a play-by-play from the logs:
> {code}
> 813572 2011-03-18 20:31:44,687 DEBUG
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter: Splitting hlog 34 of
> 35:
> hdfs://sv2borg170:9000/hbase/.logs/sv2borg182,60020,1300384550664/sv2borg182%3A60020.1300461329481,
> length=150 65662813573 2011-03-18 20:31:44,687 INFO
> org.apache.hadoop.hbase.util.FSUtils: Recovering file
> hdfs://sv2borg170:9000/hbase/.logs/sv2borg182,60020,1300384550664/sv2borg182%3A60020.1300461329481
> ....
> 813617 2011-03-18 20:31:46,238 INFO org.apache.hadoop.fs.FSInputChecker:
> Found checksum error: b[0,
> 512]=000000cd000000502037383661376439656265643938636463343433386132343631323633303239371d6170695f6163636573735f746f6b656e5f7374
>
> 6174735f6275636b65740000000d9fa4d5dc0000012ec9c7cbaf00ffffffff000000010000006d0000005d00000008002337626262663764626431616561366234616130656334383436653732333132643a32390764656661756c746170695f616e64726f69645f6c6f67676564
>
> 696e5f73686172655f70656e64696e675f696e69740000012ec956b02804000000000000000100000000ffffffff4e128eca0eb078d0652b0abac467fd09000000cd000000502034663166613763666165333930666332653138346233393931303132623366331d6170695f6163
>
> 636573735f746f6b656e5f73746174735f6275636b65740000000d9fa4d5dd0000012ec9c7cbaf00ffffffff000000010000006d0000005d00000008002366303734323966643036323862636530336238333938356239316237386633353a32390764656661756c746170695f61
>
> 6e64726f69645f6c6f67676564696e5f73686172655f70656e64696e675f696e69740000012ec9569f1804000000000000000100000000000000d30000004e2066663763393964303633343339666531666461633761616632613964643631331b6170695f6163636573735f746f
> 6b656e5f73746174735f68
> 813618 org.apache.hadoop.fs.ChecksumException: Checksum error:
> /blk_7781725413191608261:of:/hbase/.logs/sv2borg182,60020,1300384550664/sv2borg182%3A60020.1300461329481
> at 15064576
> 813619 at
> org.apache.hadoop.fs.FSInputChecker.verifySum(FSInputChecker.java:277)
> 813620 at
> org.apache.hadoop.fs.FSInputChecker.readChecksumChunk(FSInputChecker.java:241)
> 813621 at
> org.apache.hadoop.fs.FSInputChecker.fill(FSInputChecker.java:176)
> 813622 at
> org.apache.hadoop.fs.FSInputChecker.read1(FSInputChecker.java:193)
> 813623 at
> org.apache.hadoop.fs.FSInputChecker.read(FSInputChecker.java:158)
> 813624 at
> org.apache.hadoop.hdfs.DFSClient$BlockReader.read(DFSClient.java:1175)
> 813625 at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.readBuffer(DFSClient.java:1807)
> 813626 at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.read(DFSClient.java:1859)
> 813627 at java.io.DataInputStream.read(DataInputStream.java:132)
> 813628 at java.io.DataInputStream.readFully(DataInputStream.java:178)
> 813629 at
> org.apache.hadoop.io.DataOutputBuffer$Buffer.write(DataOutputBuffer.java:63)
> 813630 at
> org.apache.hadoop.io.DataOutputBuffer.write(DataOutputBuffer.java:101)
> 813631 at
> org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1937)
> 813632 at
> org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1837)
> 813633 at
> org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1883)
> 813634 at
> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader.next(SequenceFileLogReader.java:198)
> 813635 at
> org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader.next(SequenceFileLogReader.java:172)
> 813636 at
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.parseHLog(HLogSplitter.java:429)
> 813637 at
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLog(HLogSplitter.java:262)
> 813638 at
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.splitLog(HLogSplitter.java:188)
> 813639 at
> org.apache.hadoop.hbase.master.MasterFileSystem.splitLog(MasterFileSystem.java:197)
> 813640 at
> org.apache.hadoop.hbase.master.MasterFileSystem.splitLogAfterStartup(MasterFileSystem.java:181)
> 813641 at
> org.apache.hadoop.hbase.master.HMaster.finishInitialization(HMaster.java:384)
> 813642 at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:283)
> 813643 2011-03-18 20:31:46,239 WARN org.apache.hadoop.hdfs.DFSClient: Found
> Checksum error for blk_7781725413191608261_14589573 from 10.20.20.182:50010
> at 15064576
> 813644 2011-03-18 20:31:46,240 INFO org.apache.hadoop.hdfs.DFSClient: Could
> not obtain block blk_7781725413191608261_14589573 from any node:
> java.io.IOException: No live nodes contain current block. Will get new block
> locations from namenode and retry...
> 813645 2011-03-18 20:31:49,243 DEBUG
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter: Pushed=80624 entries
> from
> hdfs://sv2borg170:9000/hbase/.logs/sv2borg182,60020,1300384550664/sv2borg182%3A60020.1300461329481
> ....
> {code}
> See code above. On exception we'll dump edits read so far from this block,
> close out all writers tying off recovered.edits so far written. We'll skip
> archiving these files because we only archive if all files are processed; we
> won't archive files 30 of 35 if we failed splitting on file 31.
> I think checksumexception should be treated same as a ParseException
>
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