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https://issues.apache.org/jira/browse/FLINK-27549?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ran Tao updated FLINK-27549:
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Attachment: screenshot-2.png
> Inconsistent bytecode version when enable jdk11 or higher version
> -----------------------------------------------------------------
>
> Key: FLINK-27549
> URL: https://issues.apache.org/jira/browse/FLINK-27549
> Project: Flink
> Issue Type: Bug
> Components: API / Scala
> Affects Versions: 1.15.0, 1.14.4
> Reporter: Ran Tao
> Priority: Major
> Attachments: screenshot-1.png, screenshot-2.png
>
>
> Current flink project build with jdk1.8 is ok.
> when enable jdk11, it has some scenarios.
> 1. Using jdk11 but source 1.8 target 1.8 it's ok.
> 2. Using jdk11 and with jdk11-target source 11 and target 11. build java ok.
> But the generated bytecode version of scala class is already 52(jdk8). We
> can test with any of a scala class under jdk11 build result. e.g.
> {code:java}
> javap -verbose AggregateDataSet.class | grep major
> major version: 52
> {code}
> I have test many times and make conclusion that flink jdk11 now is not a
> completed and pure jdk11 version because of inconsistent bytecode version
> with java & scala. And it may cause some problems, for example:
> 1. inconsistent bytecode version between java & scala
> 2. Using reflection about class may generate some unkown errors
> 3. Runtime jdk11 environment can not optimize these lower bytecode.
> I have dipped into this problem and found out we must upgrade scala to
> 2.13(2.11 & 2.12 only support generate bytecode version <=1.8). the 2.13 can
> support generate scala target 11 bytecode and higher and jdk8.( By the way,
> even if scala-2.12 support generare 11 bytecode, current flink build also
> fail. Because the config about scala-maven-plugin is error, the correct
> format about jdk11 is target:11 not target:jvm-11, the latter format only for
> <=1.8 with scala-2.11 and 2.12)
> {code:java}
> <plugin>
> <groupId>net.alchim31.maven</groupId>
>
> <artifactId>scala-maven-plugin</artifactId>
> <version>3.2.2</version>
> <configuration>
> <args>
> <arg>-nobootcp</arg>
>
> <arg>-target:jvm-${target.java.version}</arg>
> </args>
> <jvmArgs>
> <arg>-Xss2m</arg>
> </jvmArgs>
> </configuration>
> </plugin>
> {code}
> I wonder current the community whether to support the completed jdk11
> version? and if not, at least we need to comment in pom or flink docs to let
> users know about this problem?
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