[jira] [Commented] (MCOMPILER-205) maven-compiler-plugin: incremental compilation broken

["Zalán Meggyesi (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MCOMPILER-205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16751997#comment-16751997 ] 

Zalán Meggyesi commented on MCOMPILER-205:
------------------------------------------

Looking at [~rfscholte]'s comment
{quote}Looking at the code, you'll see that non-incremental will only look at changed sourcefiles. Incremental will also verifies if dependencies have changed and if files have been added or removed. If it has changed, it'll remove the complete classes-directory.
{quote}
I'm having second thoughts about this. I have a project of 2805 source files, and with the default parameters, running {{mvn compile}} twice in a row takes the same time, logging the compilation of 2085 files each time. On the other hand, by setting the parameter to false, the second compilation finishes much faster, compiling only three files. To be clear, I'm running the commands literally one after the other, so there is no way dependencies could have changed in the interim.

Reading Robert's comment, it seems to me that with the default incremental compilation enabled, running the same command twice immediately should produce an equally short run, since no dependencies have changed nor any files added or removed, which would preserve the classes directory and short-circuit the Java compiler.

Obviously, I'm misunderstanding _something_ - but what?

> maven-compiler-plugin: incremental compilation broken
> -----------------------------------------------------
>
>                 Key: MCOMPILER-205
>                 URL: https://issues.apache.org/jira/browse/MCOMPILER-205
>             Project: Maven Compiler Plugin
>          Issue Type: Bug
>    Affects Versions: 3.1
>            Reporter: Lukas Fryc
>            Priority: Major
>         Attachments: hello.tgz, ignore-package-info.patch, no-class-in-java-file.zip, only-recompile-changed.patch
>
>
> When we do {{clean}} -> {{compile}} -> {{compile}}, all Java sources are re-compiled for second compilation steps:
> {code}
> [framework]$ mvn clean
> ...
> [framework]$ mvn compile
> ...
> [INFO] --- maven-compiler-plugin:3.1:compile (precompile-sources-for-cdk) @ richfaces-framework ---
> [INFO] Changes detected - recompiling the module!
> [INFO] Compiling 915 source files to /mnt/workspace/workspaces/richfaces/richfaces5/framework/target/classes
> ...
> [framework]$ mvn compile
> ...
> [INFO] --- maven-compiler-plugin:3.1:compile (precompile-sources-for-cdk) @ richfaces-framework ---
> [INFO] Changes detected - recompiling the module!
> [INFO] Compiling 915 source files to /mnt/workspace/workspaces/richfaces/richfaces5/framework/target/classes
> ...
> {code}
> The source code of the affected project: https://github.com/richfaces/richfaces5/tree/077dcfc0a46d03d7ba9a7ac3e701a4adfb834c71



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