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Kuhu Shukla commented on TEZ-3972: ---------------------------------- [~jeagles], request for review. Thanks! Test failure is unrelated. Javac warnings are not introduced by the patch as in the previous precommits too. > Tez DAG can hang when a single task fails to fetch > -------------------------------------------------- > > Key: TEZ-3972 > URL: https://issues.apache.org/jira/browse/TEZ-3972 > Project: Apache Tez > Issue Type: Bug > Affects Versions: 0.9.1 > Reporter: Kuhu Shukla > Assignee: Kuhu Shukla > Priority: Major > Attachments: TEZ-3972.001.patch, TEZ-3972.002.patch > > > Description of the hung DAG: > A DAG with 2 vertices. {{Map}} Vertex has 22k maps, downstream vertex > {{Reduce}} has 1009 tasks. All tasks succeed but one, which hangs. This one > task (attempt) is doing a local fetch from a node that (now) has a bad disk. > It fails to fetch and reports to the AM for the offending input attempt > identifiers. However the AM does not schedule a re-run as > {{uniquefailedOutputReports}} size is 1 (since only this task attempt failed > to fetch) and failure fraction is not met. The denominator for this fraction > is the total number of tasks. That causes the re-run to never occur. This > JIRA tracks the AM side of the change to alleviate this problem. -- This message was sent by Atlassian JIRA (v7.6.3#76005)