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https://issues.apache.org/jira/browse/FLINK-9913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16576422#comment-16576422
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ASF GitHub Bot commented on FLINK-9913:
---------------------------------------
pnowojski commented on a change in pull request #6417: [FLINK-9913][runtime]
Improve output serialization only once in RecordWriter
URL: https://github.com/apache/flink/pull/6417#discussion_r209290136
##########
File path:
flink-runtime/src/test/java/org/apache/flink/runtime/io/network/api/writer/RecordWriterTest.java
##########
@@ -524,6 +615,31 @@ public void read(DataInputView in) throws IOException {
}
}
+ /**
+ * Broadcast channel selector that selects all the output channels.
+ */
+ private static class Broadcast<T extends IOReadableWritable> implements
ChannelSelector<T> {
+
+ private int[] returnChannel;
+ boolean set;
Review comment:
1. do we need to cache `returnChannel`? Does it give any meaningful test
execution speed up?
2. if so, instead of using `set` and `setNumber`, just check whether
`returnChannel.length == numberOfOutputChannels`. If not, create new one.
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> 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: 1.6.0
> Reporter: zhijiang
> Assignee: zhijiang
> Priority: Minor
> 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.
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