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https://issues.apache.org/jira/browse/FLINK-9913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16605750#comment-16605750
]
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_r215611481
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/api/writer/RecordWriter.java
##########
@@ -197,40 +214,39 @@ public void setMetricGroup(TaskIOMetricGroup metrics) {
* Marks the current {@link BufferBuilder} as finished and clears the
state for next one.
*/
private void tryFinishCurrentBufferBuilder(int targetChannel) {
- if (bufferBuilders[targetChannel].isPresent()) {
- BufferBuilder bufferBuilder =
bufferBuilders[targetChannel].get();
+ Optional<BufferBuilder> bufferBuilderOpt =
bufferBuilders[targetChannel];
+ if (bufferBuilderOpt.isPresent()) {
bufferBuilders[targetChannel] = Optional.empty();
- numBytesOut.inc(bufferBuilder.finish());
+ numBytesOut.inc(bufferBuilderOpt.get().finish());
numBuffersOut.inc();
}
}
-
+
/**
* The {@link BufferBuilder} may already exist if not filled up last
time, otherwise we need
* request a new one for this target channel.
*/
- @Nonnull
private BufferBuilder getBufferBuilder(int targetChannel) throws
IOException, InterruptedException {
- if (bufferBuilders[targetChannel].isPresent()) {
- return bufferBuilders[targetChannel].get();
+ Optional<BufferBuilder> bufferBuilderOpt =
bufferBuilders[targetChannel];
+ if (bufferBuilderOpt.isPresent()) {
+ return bufferBuilderOpt.get();
} else {
return requestNewBufferBuilder(targetChannel);
}
}
- @Nonnull
private BufferBuilder requestNewBufferBuilder(int targetChannel) throws
IOException, InterruptedException {
checkState(!bufferBuilders[targetChannel].isPresent());
-
BufferBuilder bufferBuilder =
targetPartition.getBufferProvider().requestBufferBuilderBlocking();
bufferBuilders[targetChannel] = Optional.of(bufferBuilder);
targetPartition.addBufferConsumer(bufferBuilder.createBufferConsumer(),
targetChannel);
return bufferBuilder;
}
private void closeBufferBuilder(int targetChannel) {
- if (bufferBuilders[targetChannel].isPresent()) {
- bufferBuilders[targetChannel].get().finish();
+ Optional<BufferBuilder> bufferBuilderOpt =
bufferBuilders[targetChannel];
Review comment:
ditto: rename or inline
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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: 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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