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https://issues.apache.org/jira/browse/FLINK-19441?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17208828#comment-17208828
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Stephan Ewen commented on FLINK-19441:
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I could not find anything very suspicious in the code. In general, the code
does look less complex not than before, does not have any new locks or volatile
variable accesses, and seems to have the same number of virtual method calls:
- RecordWriter.emit(T record) (bi-morphic between
{{ChannelSelectorRecordWriter}} and {{BroadcastRecordWriter}}.
- The record serialization (to byte buffer) is unchanged
- Because the record-to-buffer logic is in the {{ResultPartition}} now, there
is one method on ResultPartition that is called per record now, rather than per
buffer. That method is not virtual, though, there is only one active
implementation.
One think we can investigate is the
{{ConsumableNotifyingResultPartitionWriterDecorator}}. The class is always
loaded, but never instantiated (only a static method is used). That means in
CHA the JIT will find two methods for the last method mentioned above, but all
call sites call the same one, so any profiling logic should be able to cut this
out again.
Still, it is trivial to change the code so that the
{{ConsumableNotifyingResultPartitionWriterDecorator}} code is never loaded.
Here is the PR for that: https://github.com/apache/flink/pull/13548
> Performance regression on 24.09.2020
> ------------------------------------
>
> Key: FLINK-19441
> URL: https://issues.apache.org/jira/browse/FLINK-19441
> Project: Flink
> Issue Type: Bug
> Reporter: Arvid Heise
> Assignee: Stephan Ewen
> Priority: Blocker
> Labels: pull-request-available
>
> A couple of benchmarks are showing a small performance regression on
> 24.09.2020:
> http://codespeed.dak8s.net:8000/timeline/?ben=globalWindow&env=2
> http://codespeed.dak8s.net:8000/timeline/?ben=tupleKeyBy&env=2 (?)
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