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https://issues.apache.org/jira/browse/LUCENE-10255?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dawid Weiss reassigned LUCENE-10255:
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Assignee: Dawid Weiss
> Fully embrace the java module system
> ------------------------------------
>
> Key: LUCENE-10255
> URL: https://issues.apache.org/jira/browse/LUCENE-10255
> Project: Lucene - Core
> Issue Type: New Feature
> Reporter: Dawid Weiss
> Assignee: Dawid Weiss
> Priority: Major
> Attachments: screenshot-1.png, screenshot-2.png
>
> Time Spent: 29h
> Remaining Estimate: 0h
>
> I've experimented a bit trying to move the code to the JMS. It is
> _surprisingly difficult_... A PoC that almost passes all checks is here:
> -https://github.com/dweiss/lucene/tree/jms-
> https://github.com/dweiss/lucene/tree/jms2
> Here are my conclusions so far:
> * The JMS and gradle add a lot of complexity (this applies to any
> higher-level tooling, including IDEs, I think). For starters, -modules have
> to be JARs. The effect of this is that what was previously a set of
> directories from dependencies now has to be a JAR. What was previously an
> incremental update of a single .class file now ripples throughout the build
> recreating module JARs (ZIPs!)... I didn't realize it at first, but it's a
> costly thing to do. I'm not even sure how IDEs handle this issue.- (not true)
> * A Java module contains metadata (such as the module version or main class)
> that is completely detached from any source file. These things live in a
> class bytecode of the compiled module-info; interestingly, there is no
> source-level way to specify it - these class attributes are injected by the
> 'jar' tool. Gradle has some fancy on-the-fly asm conversion filter that
> injects it.
> * Dependencies between modules will effectively live in two places: in gradle
> build files and in module-info files. -And they can go out of sync, although
> it's probably easy to catch (since javac would complain about missing classes
> during compilation, even if they're in module path).- (with separate module
> and classpath configurations there is a possibility to verify the
> consistency).
> * Probably the biggest challenge (not covered in the PoC) are with our custom
> javadoc and ecj linter tasks - they see the module-info.java and can't cope
> with it. At the same time, there is no easy way to exclude that one
> particular file: ecj would have to accept a full set of sources (command
> argument limit will be a problem), javac can accept a full set of java
> sources (external file) but then it doesn't copy doc-files properly anymore
> (this is probably easier to fix).
> * There are differences at runtime that are hard to anticipate - for example
> resource lookups via class loader no longer work (I fixed this in Luke).
> * We will have to rethink the long-term strategy of how white-box tests work.
> There are some guidelines here but all of them have some cons (IDEs being
> confused).
> https://docs.gradle.org/current/userguide/java_testing.html#sec:java_testing_modular
> * it's pretty much impossible to exclude transitive dependencies from modules
> we depend on - if they're not compile-time only (static) requirements, they
> will have to be present on module path.
> * supporting modules may or may not work in your IDE.
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