Parent pom (in multi-module project) permanently cached after first build

[pn-santos]

Affected version

1.0.3

Bug description

In a multi-module project, e.g.

├── module-1
│   ├── src
│   └── pom.xml
├──module-2
│   ├── src
│   └── pom.xml
└── pom.xml

after the first (per mvnd instance) build is run (from the root of the project), e.g.

mvnd package

the (multi-module) parent pom seems to be persistently cached by mvnd. Changes to the parent pom are simply ignored until the mvnd is restarted.

Be it

mvnd package

or even

mvnd clean package

will re-use the parent pom that was initially loaded.

If any of the modules pom files are changed though, that is picked up by mvnd. But the project parent pom seems to never be refreshed/reloaded. Doing

mvnd --stop

followed by

mvnd package

will pick up the changed parent pom.

In a non multi-module project no such issue occurs.

If I use mvn I have no such issue.

My mvnd command is aliased to this (not sure if relevant):

mvnd -ntp \
  -s path/to/maven/settings.xml \
  -Dmaven.repo.local=path/to/local/repo \
  -Daether.dependencyCollector.impl=bf

[cstamas]

My sus fix is this: #1432

Can you please locally build mvnd-1.x branch and test?

[pn-santos]

Hi @cstamas I built 794ca63 locally:

Apache Maven Daemon (mvnd) 1.0.4-SNAPSHOT linux-amd64 native client (794ca63ff25a89ca8c5ee0e694baef5c7ce9ac0c)
Terminal: org.jline.terminal.impl.PosixSysTerminal with pty org.jline.terminal.impl.jni.linux.LinuxNativePty
Apache Maven 3.9.12 (848fbb4bf2d427b72bdb2471c22fced7ebd9a7a1)
Maven home: /opt/maven-daemon/local/mvn
Java version: 21.0.2, vendor: GraalVM Community, runtime: /opt/java/graalvm-community-openjdk-21.0.2+13.1
Default locale: en_GB, platform encoding: UTF-8
OS name: "linux", version: "6.8.0-90-generic", arch: "amd64", family: "unix"

And it doesn't seem to fix the issue.

Not sure if it helps, but from what I can tell, the issue happens when properties that are only referenced by sub-project / child poms are modified.

If I change a properties version that is referenced in the pom dependencyManagement (of that same pom), mvnd seems to pick that up. But if the properties version is only referenced by the child poms, mvnd seems to keep in cache/memory the last time it parsed/built the parent pom and ignore the change.

With something like this:

  <modules>
    <module>abc</module>
    <module>xyz</module>
  </modules>

  <properties>
    <a.version>1.2.3</a.version>
    <b.version>4.5.6</b.version> <!-- only referenced in module xyz pom -->
  <properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.example</groupId>
        <artifactId>dependency</artifactId>
        <version>${a.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

If I change a.version that is picked up. If I change b.version mvnd will not pick it up. It will use the b.version of the initial build, even if that build was not valid. e.g. if the version doesn't exist the first build will fail, if I then update the b.version to the correct value, the build will still fail because it's attempted with the initial invalid version. It only after mvnd is restarted that the change is picked up.

Also another thing that could be related, the parent pom of the project has a "fixed" version (1.0):

  <groupId>com.example</groupId>
  <artifactId>parent-pom</artifactId>
  <packaging>pom</packaging>
  <version>1.0</version>

I just tried and it seems that if I use 1.0-SNAPSHOT the issue doesn't happen and any change is picked up.

The reason we use a fixed version is because we never actually publish the parent-pom. We flatten all published modules and the parent-pom only defines dependencyManagement, profiles and some properties. To avoid having to manage the parent pom version (and have to publish it) we opted to use a fixed 1.0 value and flatten all published modules, in a way trying to get the "consumer pom" behaviour of the upcoming maven 4.0

Still maven doesn't have this issue with the fixed version, only mvnd

[cstamas]

@gnodet ping