[jira] [Updated] (BEAM-839) The DirectRunner slows down significantly as the number of keys increases

["Davor Bonaci (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/BEAM-839?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Davor Bonaci updated BEAM-839:
------------------------------
    Component/s: runner-direct

> The DirectRunner slows down significantly as the number of keys increases
> -------------------------------------------------------------------------
>
>                 Key: BEAM-839
>                 URL: https://issues.apache.org/jira/browse/BEAM-839
>             Project: Beam
>          Issue Type: Bug
>          Components: runner-direct
>            Reporter: Thomas Groh
>            Assignee: Thomas Groh
>             Fix For: 0.4.0-incubating
>
>
> For example, running WordCount on KingLear takes approximately 10 seconds, while running WordCount on all of Shakespeare takes approximately 5 minutes. The primary cost is maintaining a PriorityQueue of Watermark Holds, which takes {{O(n**2)}} time, where {{n}} is the number of keys at a step.
> Additionally, there are two other things that cause slowness. The first is use of UUID.randomUUID in the constructor of DelegatingAggregator, which uses a shared SecureRandom, which synchronizes on call to {{nextBytes(byte[])}}



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