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Sergey Nuyanzin commented on FLINK-34148: ----------------------------------------- Seems I didn't get your initial question, sorry yes that's a good question. To be honest I don't know the exact answer. However what we have so far: 1. I checked that it's reproducible only for jdk8 among LTS (didn't check 9, 10) , e.g. for 11, 17 it is not reproducible, looks like it was fixed at some point on jdk level 2. I was not able to find any noticeable thing in profiler 3. Bisect shows that this perf regression comes with update of shading plugin (and changed behavior as mentioned above) I tend to think that it could relate to something like classloading or SPI since without the fix amount of classes is bigger however as I mentioned this is only a hypotheses > Potential regression (Jan. 13): stringWrite with Java8 > ------------------------------------------------------ > > Key: FLINK-34148 > URL: https://issues.apache.org/jira/browse/FLINK-34148 > Project: Flink > Issue Type: Improvement > Components: API / Type Serialization System > Reporter: Zakelly Lan > Assignee: Sergey Nuyanzin > Priority: Blocker > Fix For: 1.19.0 > > > Significant drop of performance in stringWrite with Java8 from commit > [881062f352|https://github.com/apache/flink/commit/881062f352f8bf8c21ab7cbea95e111fd82fdf20] > to > [5d9d8748b6|https://github.com/apache/flink/commit/5d9d8748b64ff1a75964a5cd2857ab5061312b51] > . It only involves strings not so long (128 or 4). > stringWrite.128.ascii(Java8) baseline=1089.107756 current_value=754.52452 > stringWrite.128.chinese(Java8) baseline=504.244575 current_value=295.358989 > stringWrite.128.russian(Java8) baseline=655.582639 current_value=421.030188 > stringWrite.4.chinese(Java8) baseline=9598.791964 current_value=6627.929927 > stringWrite.4.russian(Java8) baseline=11070.666415 current_value=8289.95767 -- This message was sent by Atlassian Jira (v8.20.10#820010)