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Shohei Okumiya commented on TEZ-4569: ------------------------------------- I confirmed that the reported issue would not happen with this patch and that 1k Hive queries succeeded. https://github.com/apache/tez/pull/361 > SCATTER_GATHER + BROADCAST hangs on DAG Recovery > ------------------------------------------------ > > Key: TEZ-4569 > URL: https://issues.apache.org/jira/browse/TEZ-4569 > Project: Apache Tez > Issue Type: Improvement > Affects Versions: 0.9.2, 0.10.3 > Reporter: Shohei Okumiya > Assignee: Shohei Okumiya > Priority: Major > Attachments: image-2024-06-11-20-45-12-540.png > > Time Spent: 0.5h > Remaining Estimate: 0h > > A Tez DAG fails to initialize itself when an Application Master is timely > preempted. > > The problem typically happens with Map Join(Broadcast Hash Join) of Hive when > the broadcast edge is multi-staged. In the following case, the smaller side > includes one aggregation, and the condition is satisfied. > > {code:java} > CREATE TABLE small AS SELECT 1 AS id; > CREATE TABLE big AS SELECT 1 AS id UNION ALL SELECT 2 AS id UNION ALL SELECT > 3 AS id; > SELECT * > FROM big > JOIN (SELECT id, count(*) AS num FROM small GROUP BY id) s ON big.id = s.id > {code} > Once it happens, a retried AM fails to configure the Map Join vertex. In the > following case, Map 1 never starts. > > > {code:java} > ---------------------------------------------------------------------------------------------- > VERTICES MODE STATUS TOTAL COMPLETED RUNNING PENDING > FAILED KILLED > ---------------------------------------------------------------------------------------------- > Map 2 .......... container SUCCEEDED 1 1 0 0 > 0 1 > Reducer 3 ...... container SUCCEEDED 1 1 0 0 > 0 0 > Map 1 container INITIALIZING -1 0 0 -1 > 0 0 > ---------------------------------------------------------------------------------------------- > {code} > Tez starts Map 2 and Map 1 once their splits are configured. The hang issue > happens when an AM is retried before it starts Reducer 3. > !image-2024-06-11-20-45-12-540.png! > -- This message was sent by Atlassian Jira (v8.20.10#820010)