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Date: Fri, 18 Nov 2016 14:49:58 +0000 (UTC)
From: "Paris Carbone (JIRA)" <jira@apache.org>
To: issues@flink.apache.org
Message-ID: <JIRA.12846666.1437510212000.313576.1479480598364@Atlassian.JIRA>
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Subject: [jira] [Updated] (FLINK-2390) Replace iteration timeout with
 algorithm for detecting termination
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archived-at: Fri, 18 Nov 2016 14:50:00 -0000


     [ https://issues.apache.org/jira/browse/FLINK-2390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paris Carbone updated FLINK-2390:
---------------------------------
    Assignee:     (was: Paris Carbone)

> 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: Streaming
>            Reporter: Gyula Fora
>             Fix For: 1.0.0
>
>
> 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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