[FLINK-30501] Update Flink build instruction to deprecate Java 8 instead of requiring Java 11

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.17.0
• Component/s: Build System / CI
• Labels: pull-request-available
• Assignee: Dong Lin
• Reporter: Dong Lin
• Created: 25/Dec/22 08:34
• Updated: 06/Mar/23 03:01
• Resolved: 06/Mar/23 02:56

Description

Flink 1.15 and later versions require at least Java 11 to build from sources [1], whereas the pom.xml specifies the source/target is 1.8. This inconsistency confuses users.

As mentioned in the FLINK-25247 title, the goal of that ticket is to "Inform users about deprecation". It will be better to inform users that "Java 8 is deprecated" instead of saying "Fink requires at least Java 11 to build", so that users have the right information to make the right choice for themselves.

Also note that Flink community is regularly running flink-ml benchmark for both Java 8 and Java 11 [2], which suggests that we are practically ensuring Java 8 is supported.

If we decide to official drop Java 8 support, Flink community probably should give explicit notice regarding the deprecation period so that users can be prepared for this breaking change. We can follow the Kafka website doc [3] for example, which says "Java 8, Java 11, and Java 17 are supported. Note that Java 8 support has been deprecated since Apache Kafka 3.0 and will be removed in Apache Kafka 4.0".

[1] https://nightlies.apache.org/flink/flink-docs-release-1.15/docs/flinkdev/building/
[2] http://codespeed.dak8s.net:8000/timeline/?ben=mapSink.F27_UNBOUNDED&env=2
[3] https://kafka.apache.org/documentation/

Issue Links

• links to: GitHub Pull Request #21557
• links to: GitHub Pull Request #22092