[jira] [Resolved] (FLINK-9913) Improve output serialization only once in RecordWriter

["Piotr Nowojski (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-9913?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Piotr Nowojski resolved FLINK-9913.
-----------------------------------
    Resolution: Fixed

merged commit 914dffb into apache:master

> Improve output serialization only once in RecordWriter
> ------------------------------------------------------
>
>                 Key: FLINK-9913
>                 URL: https://issues.apache.org/jira/browse/FLINK-9913
>             Project: Flink
>          Issue Type: Improvement
>          Components: Network
>    Affects Versions: 1.5.0, 1.5.1, 1.5.2, 1.5.3, 1.6.0
>            Reporter: zhijiang
>            Assignee: zhijiang
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.7.0
>
>
> Currently the {{RecordWriter}} emits output into multi channels via {{ChannelSelector}}  or broadcasts output to all channels directly. Each channel has a separate {{RecordSerializer}} for serializing outputs, that means the output will be serialized as many times as the number of selected channels.
> As we know, data serialization is a high cost operation, so we can get good benefits by improving the serialization only once.
> I would suggest the following changes for realizing it.
>  # Only one {{RecordSerializer}} is created in {{RecordWriter}} for all the channels.
>  # The output is serialized into the intermediate data buffer only once for different channels.
>  # The intermediate serialization results are copied into different {{BufferBuilder}}s for different channels.
> An additional benefit by using a single serializer for all channels is that we get a potentially significant reduction on heap space overhead from fewer intermediate serialization buffers (only once we got over 5MiB, these buffers were pruned back to 128B!).



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