[jira] [Commented] (BEAM-702) Simple pattern for per-bundle and per-DoFn Closeable resources

["Eugene Kirpichov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BEAM-702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15543109#comment-15543109 ] 

Eugene Kirpichov commented on BEAM-702:
---------------------------------------

CC: [~tgroh]

> Simple pattern for per-bundle and per-DoFn Closeable resources
> --------------------------------------------------------------
>
>                 Key: BEAM-702
>                 URL: https://issues.apache.org/jira/browse/BEAM-702
>             Project: Beam
>          Issue Type: Improvement
>            Reporter: Eugene Kirpichov
>
> Dealing with Closeable resources inside a processElement call is easy: simply use try-with-resources.
> However, bundle- or DoFn-scoped resources, such as long-lived database connections, are less convenient to deal with: you have to open them in startBundle and conditionally close in finishBundle (likewise setup/teardown), taking special care if there's multiple resources to close all of them.
> Perhaps we should provide something like Guava's Closer to DoFn's https://github.com/google/guava/wiki/ClosingResourcesExplained. Ideally, the user would need to only write a startBundle() or setup() method, but not write finishBundle() or teardown() - resources would be closed automatically.



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