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https://issues.apache.org/jira/browse/FLINK-9913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16579689#comment-16579689
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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_r209921447
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/api/serialization/RecordSerializer.java
##########
@@ -66,29 +66,33 @@ public boolean isFullBuffer() {
}
/**
- * Starts serializing and copying the given record to the target buffer
- * (if available).
+ * Starts serializing the given record to an intermediate data buffer.
*
* @param record the record to serialize
- * @return how much information was written to the target buffer and
- * whether this buffer is full
*/
- SerializationResult addRecord(T record) throws IOException;
+ void serializeRecord(T record) throws IOException;
Review comment:
Re 1.
I was thinking about something along those lines, however I saw the need for
`close()`, because currently `SpanningRecordSerializer` reuses for multiple
records `byte[]` that hides in `dataBuffer =
serializationBuffer.wrapAsByteBuffer();` call. Is there some other way to
release/return this array back to `RecordSerializer`? Or maybe that proves that
`RecordSerializer` and `SerializedRecord` should be indeed in one class?
Re 2.
I'm not sure. This one seems like it would leak `RecordSerializer
serializer` private fields to `SerializedRecord`.
All in all, I'm not sure if the improvement here is worth the effort and
even if we would improve/simplify code here (especially this `close()` bothers
me). Also I agree that your changes in `addRecord`,
`continueWritingWithNextBufferBuilder` and `copyToBufferBuilder` makes this
code actually easier all in all, so I would be fine with merging it as is
(modulo my other comments) :)
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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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