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From "Lucas Pauchard (Jira)" <j...@apache.org>
Subject [jira] [Created] (NUTCH-2756) Segment Part problem with HDFS on distibuted mode
Date Thu, 05 Dec 2019 12:42:01 GMT
Lucas Pauchard created NUTCH-2756:
-------------------------------------

             Summary: Segment Part problem with HDFS on distibuted mode
                 Key: NUTCH-2756
                 URL: https://issues.apache.org/jira/browse/NUTCH-2756
             Project: Nutch
          Issue Type: Bug
          Components: parser
    Affects Versions: 1.15
            Reporter: Lucas Pauchard
         Attachments: 0_byte_file_screenshot.PNG

During the parsing, it happens sometimes that parts of the data on the HDFS is missing after
the parsing.
When I take a look at our HDFS, I've got this file with 0 bytes (see attachments).

After that the CrawlDB complains about this specific (corrupted?) part:
~2019-12-04 22:25:57,454 INFO mapreduce.Job: Task Id : attempt_1575479127636_0047_m_000017_2,
Status : FAILED
Error: java.io.EOFException: hdfs://jobmaster:9000/user/hadoop/crawlmultiokhttp/segment/20191204221308/crawl_parse/part-r-00004
not a SequenceFile
        at org.apache.hadoop.io.SequenceFile$Reader.init(SequenceFile.java:1964)
        at org.apache.hadoop.io.SequenceFile$Reader.initialize(SequenceFile.java:1923)
        at org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1872)
        at org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1886)
        at org.apache.hadoop.mapreduce.lib.input.SequenceFileRecordReader.initialize(SequenceFileRecordReader.java:54)
        at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.initialize(MapTask.java:560)
        at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:798)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:347)
        at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:174)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:422)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1729)
        at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:168)~

When I check the namenode logs, I don't see any error during the writing of the segment part
but one hour later, I've got the following log:
~2019-12-04 23:23:13,750 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Recovering
[Lease.  Holder: DFSClient_attempt_1575479127636_0046_r_000004_1_1307945884_1, pending creates:
2], src=/user/hadoop/crawlmultiokhttp/segment/20191204221308/parse_data/part-r-00004/index
2019-12-04 23:23:13,750 WARN org.apache.hadoop.hdfs.StateChange: BLOCK* internalReleaseLease:
All existing blocks are COMPLETE, lease removed, file /user/hadoop/crawlmultiokhttp/segment/20191204221308/parse_data/part-r-00004/index
closed.
2019-12-04 23:23:13,750 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Recovering
[Lease.  Holder: DFSClient_attempt_1575479127636_0046_r_000004_1_1307945884_1, pending creates:
1], src=/user/hadoop/crawlmultiokhttp/segment/20191204221308/crawl_parse/part-r-00004
2019-12-04 23:23:13,750 WARN org.apache.hadoop.hdfs.StateChange: BLOCK* internalReleaseLease:
All existing blocks are COMPLETE, lease removed, file /user/hadoop/crawlmultiokhttp/segment/20191204221308/crawl_parse/part-r-00004
closed.
~

This issue is hard to reproduce and I can't figure out what are the preconditions. It seems
that it just happens randomly.
Maybe the problem is coming from a bad management when we close the file.



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