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https://issues.apache.org/jira/browse/TEZ-1400?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rajesh Balamohan updated TEZ-1400:
----------------------------------

    Attachment: TEZ-1400.2.patch

Yes, "key":"tez.am.shuffle-vertex-manager.enable.auto-parallel","value":"true" 
is explicitly enabled only for certain vertices by Hive.  Further debugging 
revealed that, TezConfiguration picked up wrong "tez-site.xml" from classpath 
which had min/max settings as 0.0.  And TezConfiguration class gets initialized 
from HiveSplitGenerator (when it tries to compute the waves). Picking up wrong 
tez-site.xml caused the issue and from this point onwards configuration would 
end up loading tez-site.xml with wrong values. Attached patch here fixes
1. TezConfiguration.java should not load tez-site.xml during class 
initialization.  It should load it via constructor.
2. If payload is null, VertexManager gets DAG conf instead of amConf.

> Reducers stuck when enabling auto-reduce parallelism (MRR case)
> ---------------------------------------------------------------
>
>                 Key: TEZ-1400
>                 URL: https://issues.apache.org/jira/browse/TEZ-1400
>             Project: Apache Tez
>          Issue Type: Bug
>    Affects Versions: 0.5.0
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>              Labels: performance
>         Attachments: TEZ-1400.1.patch, TEZ-1400.2.patch, dag.dot
>
>
> In M -> R1 -> R2 case, if R1 is optimized by auto-parallelism R2 gets stuck 
> waiting for events.
> e.g
> Map 1: 0/1      Map 2: -/-      Map 5: 0/1      Map 6: 0/1      Map 7: 0/1    
>   Reducer 3: 0/23 Reducer 4: 0/1
> ...
> ...
> Map 1: 1/1      Map 2: 148(+13)/161     Map 5: 1/1      Map 6: 1/1      Map 
> 7: 1/1      Reducer 3: 0(+3)/3      Reducer 4: 0(+1)/1  <== Auto reduce 
> parallelism kicks in
> ..
> Map 1: 1/1      Map 2: 161/161  Map 5: 1/1      Map 6: 1/1      Map 7: 1/1    
>   Reducer 3: 3/3  Reducer 4: 0(+1)/1
> Job is stuck waiting for events in Reducer 4.
>  [fetcher [Reducer_3] #23] 
> org.apache.tez.runtime.library.common.shuffle.impl.ShuffleScheduler: copy(3 
> of 23 at 0.02 MB/s) <=== *Waiting for 20 more partitions, even though 
> Reducer3 has been optimized to use 3 reducers



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