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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6309) Hive incorrectly removes TaskAttempt output files if MRAppMaster fails once
Date Thu, 30 Jan 2014 00:28:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13886078#comment-13886078
] 

Ashutosh Chauhan commented on HIVE-6309:
----------------------------------------

+1

> Hive incorrectly removes TaskAttempt output files if MRAppMaster fails once
> ---------------------------------------------------------------------------
>
>                 Key: HIVE-6309
>                 URL: https://issues.apache.org/jira/browse/HIVE-6309
>             Project: Hive
>          Issue Type: Bug
>         Environment: hadoop 2.2
>            Reporter: Chun Chen
>            Assignee: Chun Chen
>            Priority: Critical
>             Fix For: 0.13.0
>
>         Attachments: HIVE-6309.patch
>
>
> We recently upgrade to hadoop2.2 and sometimes find some tables lost several data files
after a mid night ETL process. We find that these MapReduce jobs which generate the partial
tables have something in common that the MRAppMaster of which all had failed once and the
tables all left only a single data file 000000_1000.
> The following log in hive.log give us some clues of what's going on with the incorrectly
deleted data files.
> {code}
> $ grep 'hive_2014-01-24_12-33-18_507_6790415670781610350' hive.log
> 2014-01-24 12:52:43,140 WARN  exec.Utilities (Utilities.java:removeTempOrDuplicateFiles(1535))
- Duplicate taskid file removed: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000001_1000
with length 824627293. Existing file: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000000_1000
with length 824860643
> 2014-01-24 12:52:43,142 WARN  exec.Utilities (Utilities.java:removeTempOrDuplicateFiles(1535))
- Duplicate taskid file removed: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000002_1000
with length 824681826. Existing file: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000000_1000
with length 824860643
> 2014-01-24 12:52:43,149 WARN  exec.Utilities (Utilities.java:removeTempOrDuplicateFiles(1535))
- Duplicate taskid file removed: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000003_1000
with length 824830450. Existing file: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000000_1000
with length 824860643
> 2014-01-24 12:52:43,151 WARN  exec.Utilities (Utilities.java:removeTempOrDuplicateFiles(1535))
- Duplicate taskid file removed: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000004_1000
with length 824753882. Existing file: hdfs://hadoop00.lf.sankuai.com:9000/tmp/hive-scratch/hive-sankuai/hive_2014-01-24_12-33-18_507_6790415670781610350/_tmp.-ext-10000.intermediate/000000_1000
with length 824860643
> {code}
> We find that it's because nextAttemptNumber in hadoop2.2 is bigger than 1000 and hive
doesn't correctly extract task id from filename. See the following code in org.apache.hadoop.mapreduce.v2.app.job.impl.TaskImpl.java
> and ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java
> {code}
> // org.apache.hadoop.mapreduce.v2.app.job.impl.TaskImpl.java
>     // All the new TaskAttemptIDs are generated based on MR
>     // ApplicationAttemptID so that attempts from previous lives don't
>     // over-step the current one. This assumes that a task won't have more
>     // than 1000 attempts in its single generation, which is very reasonable.
>     nextAttemptNumber = (appAttemptId - 1) * 1000;
> // ql/src/java/org/apache/hadoop/hive/ql/exec/Utilities.java
>    /**
>     * The first group will contain the task id. The second group is the optional extension.
The file
>     * name looks like: "0_0" or "0_0.gz". There may be a leading prefix (tmp_). Since
getTaskId() can
>     * return an integer only - this should match a pure integer as well. {1,3} is used
to limit
>     * matching for attempts #'s 0-999.
>     */
>    private static final Pattern FILE_NAME_TO_TASK_ID_REGEX =
>        Pattern.compile("^.*?([0-9]+)(_[0-9]{1,3})?(\\..*)?$");
> {code}
> And with the bellow reasons,  extract this value for attempt numbers >= 1000 : 
> {code}
> >>> re.match("^.*?([0-9]+)(_[0​-9])?(\\..*)?$", 'part-r-000000_2').group(1)
> '000000'
> >>> re.match("^.*?([0-9]+)(_[0​-9])?(\\..*)?$", 'part-r-000000_1001').group(1)
> '1001'
> {code}



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