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Posted to issues@flink.apache.org by "Roman Grebennikov (Jira)" <ji...@apache.org> on 2019/12/04 11:28:00 UTC
[jira] [Comment Edited] (FLINK-14346) Performance issue with
StringSerializer
[ https://issues.apache.org/jira/browse/FLINK-14346?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16987752#comment-16987752 ]
Roman Grebennikov edited comment on FLINK-14346 at 12/4/19 11:27 AM:
---------------------------------------------------------------------
[~arvid heise] current progress:
# I've modified StringSerializationBenchmark to have 1b-128b-16kb strings measured. Also StringSerializationBenchmark and PojoSerializationBenchmark are moved to full package, so they won't be included into the regular performance regression run.
# Fallback code for writeString is removed, the code modified in a way so it will work with any length of the string.
# Added a test to validate binary compatibility between new and old implementation.
{noformat}
[info] Benchmark (length) (stringType) Mode Cnt Score Error Units
[info] StringDeserializerBenchmark.deserializeDefault 1 ascii avgt 50 45.618 ± 0.339 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 2 ascii avgt 50 61.348 ± 0.579 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 4 ascii avgt 50 88.067 ± 1.058 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 8 ascii avgt 50 142.902 ± 1.121 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 16 ascii avgt 50 249.181 ± 1.920 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 32 ascii avgt 50 466.382 ± 1.502 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 1 ascii avgt 50 49.916 ± 0.132 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 2 ascii avgt 50 50.278 ± 0.064 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 4 ascii avgt 50 50.365 ± 0.129 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 8 ascii avgt 50 52.463 ± 0.301 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 16 ascii avgt 50 55.711 ± 0.597 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 32 ascii avgt 50 65.342 ± 0.555 ns/op
[info] StringSerializerBenchmark.serializeDefault 1 ascii avgt 50 31.076 ± 0.192 ns/op
[info] StringSerializerBenchmark.serializeDefault 2 ascii avgt 50 31.770 ± 1.811 ns/op
[info] StringSerializerBenchmark.serializeDefault 4 ascii avgt 50 39.251 ± 0.189 ns/op
[info] StringSerializerBenchmark.serializeDefault 8 ascii avgt 50 57.736 ± 0.253 ns/op
[info] StringSerializerBenchmark.serializeDefault 16 ascii avgt 50 94.964 ± 0.514 ns/op
[info] StringSerializerBenchmark.serializeDefault 32 ascii avgt 50 168.754 ± 1.416 ns/op
[info] StringSerializerBenchmark.serializeImproved 1 ascii avgt 50 30.145 ± 0.156 ns/op
[info] StringSerializerBenchmark.serializeImproved 2 ascii avgt 50 30.873 ± 0.274 ns/op
[info] StringSerializerBenchmark.serializeImproved 4 ascii avgt 50 31.993 ± 0.276 ns/op
[info] StringSerializerBenchmark.serializeImproved 8 ascii avgt 50 46.220 ± 0.211 ns/op
[info] StringSerializerBenchmark.serializeImproved 16 ascii avgt 50 50.856 ± 0.826 ns/op
[info] StringSerializerBenchmark.serializeImproved 32 ascii avgt 50 63.221 ± 1.130 ns/op{noformat}
was (Author: rgrebennikov):
[~arvid heise] current progress:
# I've modified StringSerializationBenchmark to have 1b-128b-16kb strings measured. Also StringSerializationBenchmark and PojoSerializationBenchmark are moved to full package, so they won't be included into the regular performance regression run.
# Fallback code for writeString is removed, the code modified in a way so it will work with any length of the string.
{noformat}
[info] Benchmark (length) (stringType) Mode Cnt Score Error Units
[info] StringDeserializerBenchmark.deserializeDefault 1 ascii avgt 50 45.618 ± 0.339 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 2 ascii avgt 50 61.348 ± 0.579 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 4 ascii avgt 50 88.067 ± 1.058 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 8 ascii avgt 50 142.902 ± 1.121 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 16 ascii avgt 50 249.181 ± 1.920 ns/op
[info] StringDeserializerBenchmark.deserializeDefault 32 ascii avgt 50 466.382 ± 1.502 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 1 ascii avgt 50 49.916 ± 0.132 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 2 ascii avgt 50 50.278 ± 0.064 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 4 ascii avgt 50 50.365 ± 0.129 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 8 ascii avgt 50 52.463 ± 0.301 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 16 ascii avgt 50 55.711 ± 0.597 ns/op
[info] StringDeserializerBenchmark.deserializeImproved 32 ascii avgt 50 65.342 ± 0.555 ns/op
[info] StringSerializerBenchmark.serializeDefault 1 ascii avgt 50 31.076 ± 0.192 ns/op
[info] StringSerializerBenchmark.serializeDefault 2 ascii avgt 50 31.770 ± 1.811 ns/op
[info] StringSerializerBenchmark.serializeDefault 4 ascii avgt 50 39.251 ± 0.189 ns/op
[info] StringSerializerBenchmark.serializeDefault 8 ascii avgt 50 57.736 ± 0.253 ns/op
[info] StringSerializerBenchmark.serializeDefault 16 ascii avgt 50 94.964 ± 0.514 ns/op
[info] StringSerializerBenchmark.serializeDefault 32 ascii avgt 50 168.754 ± 1.416 ns/op
[info] StringSerializerBenchmark.serializeImproved 1 ascii avgt 50 30.145 ± 0.156 ns/op
[info] StringSerializerBenchmark.serializeImproved 2 ascii avgt 50 30.873 ± 0.274 ns/op
[info] StringSerializerBenchmark.serializeImproved 4 ascii avgt 50 31.993 ± 0.276 ns/op
[info] StringSerializerBenchmark.serializeImproved 8 ascii avgt 50 46.220 ± 0.211 ns/op
[info] StringSerializerBenchmark.serializeImproved 16 ascii avgt 50 50.856 ± 0.826 ns/op
[info] StringSerializerBenchmark.serializeImproved 32 ascii avgt 50 63.221 ± 1.130 ns/op{noformat}
> Performance issue with StringSerializer
> ---------------------------------------
>
> Key: FLINK-14346
> URL: https://issues.apache.org/jira/browse/FLINK-14346
> Project: Flink
> Issue Type: Improvement
> Components: API / Type Serialization System, Benchmarks
> Affects Versions: 1.9.0, 1.10.0, 1.9.1
> Environment: Tested on Flink 1.10.0-SNAPSHOT-20191129-034045-139, adoptopenjdk 8u222.
> Reporter: Roman Grebennikov
> Priority: Major
> Labels: performance, pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> While doing a performance profiling for our Flink state-heavy streaming job, we found that quite a significant amount of CPU time is spent inside StringSerializer writing data to the underlying byte buffer. The hottest part of the code is the StringValue.writeString function. And replacing the default StringSerializer with the custom one (to just play with a baseline), which is just calling DataOutput.writeUTF/readUTF surprisingly yielded to almost 2x speedup for string serialization.
> As writeUTF and writeString have incompatible wire formats, replacing latter with former is not a good idea in general as it may break checkpoint/savepoint compatibility.
> We also did an early performance analysis of the root cause of this performance issue, and the main reason of JDK's writeUTF being faster is that it's code is not writing directly to output stream byte-by-byte, but instead creating an underlying temporary byte buffer. This yields to a HotSpot almost perfectly unrolling the main loop, which results in much better data parallelism.
> I've tried to port the ideas from the JVM's implementation of writeUTF back to StringValue.writeString, and my current result is nice, having quite significant speedup compared to the current implementation:
> {{[info] Benchmark Mode Cnt Score Error Units}}
> {{[info] StringSerializerBenchmark.measureJDK avgt 30 82.871 ± 1.293 ns/op}}
> {{[info] StringSerializerBenchmark.measureNew avgt 30 94.004 ± 1.491 ns/op}}
> {{[info] StringSerializerBenchmark.measureOld avgt 30 156.905 ± 3.596 ns/op}}
>
> {{Where measureJDK is the JDK's writeUTF asa baseline, measureOld is the current upstream implementation in Flink, and the measureNew is the improved one. }}
>
> {{The code for the benchmark (and the improved version of the serializer) is here: [https://github.com/shuttie/flink-string-serializer]}}
>
> {{Next steps:}}
> # {{More benchmarks for non-ascii strings.}}
> # {{Benchmarks for long strings.}}
> # {{Benchmarks for deserialization.}}
> # {{Tests for old-new wire format compatibility.}}
> # {{PR to the Flink codebase.}}
> {{Is there an interest for this kind of performance improvement?}}
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