Review on new JDK (Java 18, 19, 20)

[tesshucom]

Java 18, 19, 20 is added to the workflow. This is to make it easier to get the binary to check the operation.

• Will not be released(Currently the release page only publishes binaries for the LTS JDK).
• Binaries for the new JDK are available from the Actions#master page

Matter of interest (may be of benefit)

• JDK18
  • JEP 400: UTF-8 by Default : The default character set will change.
  • Related Add ZoneOffset to Internal help page #1689.
  • In Jpsonic, reading and writing of all files has already been rewritten on the premise of UTF-8 already. Should have no impact.
• JDK19
  • JEP 425: Virtual Threads (Preview)
  • May have limited positive impact. It doesn't seem to have enough effect to affect the multi-threaded design of Jpsonic. Or it will be subject to future verification.
  • Single-threaded scanning by default, parallelization will be provided as an option. Since it runs on a personal server, rather restrained behavior is basic behavior.
• JDK20
  • JEP 437: Structured Concurrency (Second Incubator)
  • Extension of JDK19. New APIs are welcome, but J2ee(Jakarta EE) apps will probably not use them directly. (Probably. Unless the J2ee architect changes.) We may need to turn your attention to Jetty's threading model rather.

Limitations

• EclipseLink warnings on startup still not resolved. No problems with server operation.
  • EclipseLinkASMClassWriter getLatestOPCodeVersion picking incorrect opcode version on Java 18, and displaying confusing warning
  • Resolved in Bump org.eclipse.persistence:org.eclipse.persistence.moxy from 2.7.12 to 2.7.13 #2298
    • This commit will resolve the last eclipselink.asm.version 9.3.0 dependency. In other words, even if you start with Java18 or later, the warning will not be displayed.
    • Theoretically assumed to be compilable up to JDK 21. (Validation will be done up to the version supported by the workflow script on Github. )

[tesshucom]

Java21 GA will probably be released in v111.3 or v111.4. At that time, CI and Docker are changed. Java21 war will also be distributed, and the JDK used in the Docker image will be migrated to 21.