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https://issues.apache.org/jira/browse/TEZ-1206?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14037231#comment-14037231
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Oleg Zhurakousky commented on TEZ-1206:
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The fact that we allow breaking changes between minor releases is a bit
strange, but it is what it is, so I'll look at what are the issues with 2.5.
With regard to removing code from _main()_, here are my points:
DAGAppMaster actually only takes 1 (optional) argument. The rest comes from
Environment variables and are being parsed in main, so no huge array to pass
around. But that is not the main issue. What is is that parsing arguments in
main results in DAGAppMaster having constructor with 8 arguments (already
considered an anti-pattern by many), but bigger issue is that if/when new
argument is introduced, such constructor will be modified thus introducing
another breaking change that could have been easily avoided by making the
structure and design of DAGAppMaster more stable.
Also, as you can see some of the tests need access to the actual instance of
DAGAppMaster. I can't get access to such instance using
_DAGAppMaster.main(..)_. This only leaves me with once choice and that is to
repeat some of the main(..) logic in test itself, so keeping it simple aids in
such testing.
Mocking is great and as you can see I do use it quite a lot when its
appropriate, but it requires a lot of discipline since the behavior represented
in mocks must represent the real thing, but as you already pointed out it does
not.
> Lifecycle issues with DAGAppMaster
> ----------------------------------
>
> Key: TEZ-1206
> URL: https://issues.apache.org/jira/browse/TEZ-1206
> Project: Apache Tez
> Issue Type: Bug
> Affects Versions: 0.4.0
> Reporter: Oleg Zhurakousky
> Assignee: Oleg Zhurakousky
> Attachments: TEZ-1206.patch, TEZ-1206.patch.2, TEZ-1206.patch.3.patch
>
>
> This is an umbrella issue to document and address issues with DAGAppMaster
> lifecycle
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