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https://issues.apache.org/jira/browse/FLUME-553?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ashish Paliwal resolved FLUME-553.
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Resolution: Won't Fix
Fix Version/s: v0.9.5
Won't fix. 0.X branch not maintained anymore
> collectorSink becomes unstable when hdfs goes down using e2e (but it "gets
> fixed" when restarting the collector)
> ----------------------------------------------------------------------------------------------------------------
>
> Key: FLUME-553
> URL: https://issues.apache.org/jira/browse/FLUME-553
> Project: Flume
> Issue Type: Bug
> Components: Sinks+Sources
> Affects Versions: v0.9.3
> Reporter: Disabled imported user
> Priority: Critical
> Labels: collector, sink
> Fix For: v0.9.5
>
>
> I've found a case when a collector using collectorSink (in e2e mode)
> becomes unstable if hdfs enters safeMode (and leaves it after a
> while).
> My collectorSink looks like:
>
> exec config collector02.data data-flow autoCollectorSource
> 'collectorSink("hdfs://host.namel/user/flume/input", "data-",
> 30000)'
>
> The situation would be:
> 1- The collector is saving data to hdfs properly .
> 2- I turn on safe mode on hdfs.
> 3- Collector starts failing, this is normal as can't write to hdfs.
> 4- After the collector has been failing trying to create 2 files (more
> than 30000 mili * 2) I make hdfs leave the safe mode.
> 5- Since now, even hdfs is not in safemode anymore, I will sometimes
> be getting errors like:
>
> NFO endtoend.AckChecksumChecker: Starting checksum group called log.
> 00000033.20110309-172500877+0100.1299687900877700000.seq
> 2011-03-09 17:26:12,415 [logicalNode collector02.data-25] INFO
> endtoend.AckChecksumChecker: initial checksum is 12e9b6f86ce
> 2011-03-09 17:26:12,415 [logicalNode collector02.data-25] INFO
> hdfs.EscapedCustomDfsSink: Closing
> hdfs://sturlese.local/user/flume/input/data-log.00000025.20110309-172540945
> +0100.1299687940945069000.seq
> 2011-03-09 17:26:12,415 [logicalNode collector02.data-25] INFO
> hdfs.CustomDfsSink: Closing HDFS file:
> hdfs://sturlese.local/user/flume/input/data-log.00000025.20110309-172540945
> +0100.1299687940945069000.seq
> 2011-03-09 17:26:12,415 [logicalNode collector02.data-25] INFO
> hdfs.CustomDfsSink: done writing raw file to hdfs
> 2011-03-09 17:26:12,435 [logicalNode collector02.data-25] INFO
> hdfs.EscapedCustomDfsSink: Closing
> hdfs://sturlese.local/user/flume/input/data-log.00000044.20110309-172430963
> +0100.1299687870963688000.seq
> 2011-03-09 17:26:12,435 [logicalNode collector02.data-25] INFO
> hdfs.CustomDfsSink: Closing HDFS file:
> hdfs://sturlese.local/user/flume/input/data-log.00000044.20110309-172430963
> +0100.1299687870963688000.seq
> 2011-03-09 17:26:12,435 [logicalNode collector02.data-25] INFO
> hdfs.CustomDfsSink: done writing raw file to hdfs
> 2011-03-09 17:26:12,435 [logicalNode collector02.data-25] ERROR
> rolling.RollSink: Failure when attempting to rotate and open new sink:
> org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot add
> block to /user/flume/input/data-log.
> 00000044.20110309-172430963+0100.1299687870963688000.seq. Name node is
> in safe mode.
> Use "hadoop dfsadmin -safemode leave" to turn safe mode off.
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNa
> mesystem.java:
> 1318)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:
> 469)
> at sun.reflect.Generated
> MethodAccessor11.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImp
> l.java:
> 25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:512)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:968)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:964)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:396)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:962)
> 2011-03-09 17:26:12,435 [logicalNode collector02.data-25] INFO
> hdfs.EscapedCustomDfsSink: Opening
> hdfs://host.name/user/flume/input/data-log.00000025.20110309-172612415+0100
> .1299687972415285000.seq
>
> If I refresh the collector using the shell (exec refresh
> collector02.data) the error will disappear and all data that couldn't
> be written will suddenly be (because of the e2e).
>
> Reproducing the situation many times from a
> fresh installation every time, some of them it gets recovered without
> the need of refreshing, but most of them not.
> Jonathan Hsieh tip:
> At the highest level, it seems like there is some bad state sticking
> around that doesn't get cleaned out properly when recovering.
> Internally the escaping code ends up holding many hdfs file handles
> open. My guess is that we are in a situation with multiple handles
> open and the error occurs. We properly handle one error but the other
> broken file handles (based on connections that were initiated in safe
> mode) are not cleaned up. The bad handles eventually get closed when
> a roll tries to flush them, and this is when the actual error message
> appears.
> The refresh closes everything down and the restarts it, so all the new
> connections are all good.
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