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Posted to mapreduce-dev@hadoop.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2011/03/08 22:00:59 UTC

[jira] Created: (MAPREDUCE-2371) TaskLogsTruncater does not need to check log ownership when running as Child

TaskLogsTruncater does not need to check log ownership when running as Child
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                 Key: MAPREDUCE-2371
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2371
             Project: Hadoop Map/Reduce
          Issue Type: Improvement
    Affects Versions: 0.23.0
            Reporter: Todd Lipcon
            Assignee: Todd Lipcon
             Fix For: 0.23.0


Before MAPREDUCE-2178, it used to be that the TaskLogsTruncater had to use the SecureIO API to open the task logs before truncation, to avoid an attack where the user would symlink in something that the TT had access to but not the user. After MAPREDUCE-2178, this truncation is done as the user rather than as the TT, so we don't need to perform this check.

Not performing the check avoids a fork() call which we've found to be troublesome since it doubles vmem consumption and thus requires that users bump mapred.child.ulimit to >2x the expected child heap size.

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