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https://issues.apache.org/jira/browse/FLINK-8847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16387561#comment-16387561
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ASF GitHub Bot commented on FLINK-8847:
---------------------------------------
GitHub user zentol opened a pull request:
https://github.com/apache/flink/pull/5644
[FLINK-8847][build] Prevent unnecessary recompilation
## What is the purpose of the change
This PR contains 2 changes to prevent the `maven-compiler-plugin` from
recompiling a module that doesn't require it.
The `maven-compiler-plugin` will now always create `.class` files for
`package-info.java` files. Previously this was only done if the `.java` file
contained annotations.
Having a `.java` file without a corresponding `.class` file throws of the
`maven-compiler-plugin` stale source detection, as described in
[MCOMPILER-205](https://issues.apache.org/jira/browse/MCOMPILER-205).
Additionally, `useIncrementalCompilation` is set to false which actually
enables incremental compilation, as described in
[MCOMPILER-209](https://issues.apache.org/jira/browse/MCOMPILER-209).
## Brief change log
* create `.class` files for all `package-info.java` files
* set `useIncrementalCompilation` to false which actually enables
incremental compilation
## Verifying this change
Pick any module that contains a `package-info.java` file (like
`flink-optimizer`) and run `mvn package <speed options>` twice. The plugin
should not recompile the module.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/zentol/flink 8847
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/5644.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #5644
----
commit 293795b5e5f57dba07e985be9e46ba2534e91eac
Author: zentol <chesnay@...>
Date: 2018-03-06T09:45:25Z
[FLINK-8847][build] Always generate .class files for package-info.java
commit 92d17feab6cd604fd2bd2be96d6ed35485c13b80
Author: zentol <chesnay@...>
Date: 2018-03-06T10:04:42Z
[hotfix][build] Enable incremental compilation
----
> Modules containing package-info.java are always recompiled
> ----------------------------------------------------------
>
> Key: FLINK-8847
> URL: https://issues.apache.org/jira/browse/FLINK-8847
> Project: Flink
> Issue Type: Bug
> Components: Build System
> Affects Versions: 1.3.2, 1.5.0, 1.4.1
> Reporter: Chesnay Schepler
> Assignee: Chesnay Schepler
> Priority: Minor
> Fix For: 1.5.0, 1.4.3
>
>
> All modules that contain a {{package-info.java}} file (that do not contain
> annotations which applies to *all* instances in Flink) will always be
> recompiled by the {{maven-compiler-plugin}}.
> To detect modified files the compiler compares timestamps of the source and
> .class file. In the case of {{package-info.java}} no .class file is created
> if it doesn't contain annotations, which the compiler interprets as a missing
> .class file.
> We can add {{-Xpkginfo:always}} to the compiler configuration to force the
> generation of these files to prevent this from happening.
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