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https://issues.apache.org/jira/browse/SAMZA-348?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14102616#comment-14102616
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Chinmay Soman commented on SAMZA-348:
-------------------------------------
Just for my education : are we talking about embedding a Kafka consumer inside
the YARN AM ?
The way I imagined this is that the AM will read the config from some Kafka
topic (per Samza topology) which will then initialize (or modify) containers
based on this ?
Do we also need the AM -> container communication mechanism, discussed in a
previous ticket as part of this ? OR - in case of a config change, the AM
simply destroys and re-creates the required containers ?
> Configure Samza jobs through a stream
> -------------------------------------
>
> Key: SAMZA-348
> URL: https://issues.apache.org/jira/browse/SAMZA-348
> Project: Samza
> Issue Type: Bug
> Affects Versions: 0.7.0
> Reporter: Chris Riccomini
>
> Samza's existing config setup is problematic for a number of reasons:
> # It's completely immutable once a job starts. This prevents any dynamic
> reconfiguration and auto-scaling. It is debatable whether we want these
> feature or not, but our existing implementation actively prevents it. See
> SAMZA-334 for discussion.
> # We pass existing configuration through environment variables. YARN exports
> environment variables in a shell script, which limits the size to the varargs
> length on the machine. This is usually ~128KB. See SAMZA-333 and SAMZA-337
> for details.
> # User-defined configuration (the Config object) and programmatic
> configuration (checkpoints and TaskName:State mappings (see SAMZA-123)) are
> handled differently. It's debatable whether this makes sense.
> In SAMZA-123, [~jghoman] and I propose implementing a ConfigLog. This log
> would replace both the checkpoint topic and the existing config environment
> variables in SamzaContainer and Samza's YARN AM.
> I'd like to keep this ticket's scope limited to just the implementation of
> the ConfigLog, and not re-designing how Samza's config is used in the code
> (SAMZA-40). We should, however, discuss how this feature would affect dynamic
> reconfiguration/auto-scaling.
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