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https://issues.apache.org/jira/browse/FLINK-2390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gyula Fora closed FLINK-2390.
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Resolution: Won't Fix
> Replace iteration timeout with algorithm for detecting termination
> ------------------------------------------------------------------
>
> Key: FLINK-2390
> URL: https://issues.apache.org/jira/browse/FLINK-2390
> Project: Flink
> Issue Type: New Feature
> Components: API / DataStream
> Reporter: Gyula Fora
> Priority: Major
>
> Currently the user can set a timeout which will shut down the iteration
> source/sink nodes if no new data is received during that time to allow
> program termination in iterative streaming jobs.
> This method is used due to the non-trivial nature of termination in iterative
> streaming jobs. While termination is not a main concern in long running
> streaming jobs, this behaviour makes iterative tests non-deterministic and
> they often fail on travis due to the timeout. Also setting a timeout can
> cause jobs to terminate prematurely.
> I propose to remove iteration timeouts and replace it with the following
> algorithm for detecting termination:
> -We first identify loop edges in the jobgraph (the channels from the
> iteration sources to the head operators)
> -Once the head operators (the ones with loop input) finish with all their
> non-loop inputs they broadcast a marker to their outputs.
> -Each operator will broadcast a marker once it received a marker from all its
> non-finished inputs
> -Iteration sources are terminated when they receive 2 consecutive markers
> without receiving any record in-between
> The idea behind the algorithm is to find out when no more outputs are
> generated from the operators inside an iteration after their normal inputs
> are finished.
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