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https://issues.apache.org/jira/browse/ACCUMULO-623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13295300#comment-13295300
]
Keith Turner commented on ACCUMULO-623:
---------------------------------------
I tried another experiment. Instead of killing all java processes on my single
node instance, I did the following.
* start HDFS and zookeeper
* init & start Accumulo
* created a table and insert some data
* kill data node
* kill all accumulo processes
* restart datanode
* restart accumulo
* recovery fails
Under this scenario recovery fails differently. The following is from the
tablet server logs, I get an NPE in hdfs client code.
{noformat}
14 16:26:17,253 [log.LogSorter] INFO : Zookeeper references 1 recoveries,
attempting locks14 16:26:17,254 [log.LogSorter] DEBUG: Attempting to lock
b67eb806-6ef1-4ecc-b739-a4ee90e08086
14 16:26:17,262 [log.LogSorter] INFO : got lock for
b67eb806-6ef1-4ecc-b739-a4ee90e08086
14 16:26:17,264 [log.LogSorter] INFO : Copying
/accumulo/wal/127.0.0.1+40200/b67eb806-6ef1-4ecc-b739-a4ee90e08086 to
/accumulo/recovery/b67eb806-6ef1-4ecc-b739-a4ee90e08086
14 16:26:17,300 [log.LogSorter] ERROR: Unexpected error
java.lang.NullPointerException
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.updateBlockInfo(DFSClient.java:1885)
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:1858)
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.<init>(DFSClient.java:1834)
at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:578) at
org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:154)
at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:427)
at
org.apache.accumulo.server.tabletserver.log.LogSorter.startSort(LogSorter.java:295)
at
org.apache.accumulo.server.tabletserver.log.LogSorter.attemptRecoveries(LogSorter.java:266)
at
org.apache.accumulo.server.tabletserver.log.LogSorter.access$200(LogSorter.java:60)
at
org.apache.accumulo.server.tabletserver.log.LogSorter$1.process(LogSorter.java:204)
at
org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:530)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:506)
{noformat}
> Data lost with hdfs write ahead log
> -----------------------------------
>
> Key: ACCUMULO-623
> URL: https://issues.apache.org/jira/browse/ACCUMULO-623
> Project: Accumulo
> Issue Type: Bug
> Environment: MacOSX, Hadoop 1.0.3, zookeeper 3.3.3
> Reporter: Keith Turner
> Assignee: Eric Newton
> Priority: Blocker
> Fix For: 1.5.0
>
>
> I shut my machine down with Accumulo, Zookeeper, and HDFS running. When I
> restarted it, Accumulo failed to recover its write ahead log because it was
> zero length. I wondered if this was because I shutdown HDFS so I tried the
> following on my single node Accumulo instance.
> * start HDFS and zookeeper
> * init & start Accumulo
> * created a table and insert some data
> * pkill -f java
> * restart everything
> * Accumulo fails to start because walog is zero length
> Saw excpetions like the following
> {noformat}
> 06 18:58:44,581 [log.SortedLogRecovery] INFO : Looking at mutations from
> /accumulo/recovery/def72721-5c64-4755-87cc-2e8cfc3002b7 for !0;!0<<
> 06 18:58:44,590 [tabletserver.TabletServer] WARN : exception trying to assign
> tablet !0;!0<< /root_tablet
> java.lang.RuntimeException: java.io.IOException: java.lang.RuntimeException:
> Unable to read log entries
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1458)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1295)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1134)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1121)
> at
> org.apache.accumulo.server.tabletserver.TabletServer$AssignmentHandler.run(TabletServer.java:2477)
> at
> org.apache.accumulo.core.util.LoggingRunnable.run(LoggingRunnable.java:34)
> at java.lang.Thread.run(Thread.java:680)
> Caused by: java.io.IOException: java.lang.RuntimeException: Unable to read
> log entries
> at
> org.apache.accumulo.server.tabletserver.log.TabletServerLogger.recover(TabletServerLogger.java:428)
> at
> org.apache.accumulo.server.tabletserver.TabletServer.recover(TabletServer.java:3206)
> at
> org.apache.accumulo.server.tabletserver.Tablet.<init>(Tablet.java:1426)
> ... 6 more
> Caused by: java.lang.RuntimeException: Unable to read log entries
> at
> org.apache.accumulo.server.tabletserver.log.SortedLogRecovery.findLastStartToFinish(SortedLogRecovery.java:125)
> at
> org.apache.accumulo.server.tabletserver.log.SortedLogRecovery.recover(SortedLogRecovery.java:89)
> at
> org.apache.accumulo.server.tabletserver.log.TabletServerLogger.recover(TabletServerLogger.java:426)
> ... 8 more
> {noformat}
> When trying to run LogReader on the files, it prints nothing.
> {noformat}
> $ ./bin/accumulo org.apache.accumulo.server.logger.LogReader
> /accumulo/recovery/def72721-5c64-4755-87cc-2e8cfc3002b7
> 06 19:04:37,147 [util.NativeCodeLoader] WARN : Unable to load native-hadoop
> library for your platform... using builtin-java classes where applicable
> $ ./bin/accumulo org.apache.accumulo.server.logger.LogReader
> /accumulo/wal/127.0.0.1+40200/def72721-5c64-4755-87cc-2e8cfc3002b7
> $
> {noformat}
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