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https://issues.apache.org/jira/browse/FLINK-9913?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16595115#comment-16595115
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ASF GitHub Bot commented on FLINK-9913:
---------------------------------------
zhijiangW 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_r213345034
##########
File path:
flink-runtime/src/test/java/org/apache/flink/runtime/io/network/api/serialization/SpanningRecordSerializerTest.java
##########
@@ -169,25 +167,26 @@ private void test(Util.MockRecords records, int
segmentSize) throws Exception {
//
-------------------------------------------------------------------------------------------------------------
-
serializer.continueWritingWithNextBufferBuilder(createBufferBuilder(segmentSize));
-
+ BufferBuilder bufferBuilder = createBufferBuilder(segmentSize);
int numBytes = 0;
for (SerializationTestType record : records) {
- RecordSerializer.SerializationResult result =
serializer.addRecord(record);
+ serializer.serializeRecord(record);
+ RecordSerializer.SerializationResult result =
serializer.copyToBufferBuilder(bufferBuilder);
numBytes += record.length() + serializationOverhead;
if (numBytes < segmentSize) {
Assert.assertEquals(RecordSerializer.SerializationResult.FULL_RECORD, result);
} else if (numBytes == segmentSize) {
Assert.assertEquals(RecordSerializer.SerializationResult.FULL_RECORD_MEMORY_SEGMENT_FULL,
result);
-
serializer.continueWritingWithNextBufferBuilder(createBufferBuilder(segmentSize));
+ bufferBuilder =
createBufferBuilder(segmentSize);
numBytes = 0;
} else {
Assert.assertEquals(RecordSerializer.SerializationResult.PARTIAL_RECORD_MEMORY_SEGMENT_FULL,
result);
while (result.isFullBuffer()) {
numBytes -= segmentSize;
- result =
serializer.continueWritingWithNextBufferBuilder(createBufferBuilder(segmentSize));
+ bufferBuilder =
createBufferBuilder(segmentSize);
+ result =
serializer.copyToBufferBuilder(bufferBuilder);
Review comment:
make sense
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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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