Could this plugin be marked thread safe? about ci.maven

[cherylking]

@blirp Thank you for bringing this to our attention. We would like to understand your particular use case. Can you describe your project configuration / setup?

We have no reason to believe that our goals (other than dev mode which is meant to be a single interactive session) are not thread safe, but we have not taken the step to document them as such.

[cherylking]

I have found two instances of static variables that should be looked at. One is in CommonLogger (this may be more tricky to change) and the other is in StartDebugMojoSupport (configFilesCopied variable).

[blirp]

I have a medium sized application with 44 modules in total, and about 500K of Java code. (And an unknown number of Spring XML configuration). The application is split into three main modules, 'common', 'frontend' and 'backend'. Mostly JSP. We use Liberty for both the frontend and backend modules.

My hope was that giving Maven some more threads, we could speed up build times a bit. That gave various warnings about non-thread-safe plugins. Most I could easily update, but not the liberty-maven-plugin.

[bmarwell]

I have found two instances of static variables that should be looked at. One is in CommonLogger (this may be more tricky to change) and the other is in StartDebugMojoSupport (configFilesCopied variable).

Why do you thing the static logger could be a problem? If it is final, I do not see a problem here.

and the other is in StartDebugMojoSupport (configFilesCopied variable).

This one:

ci.maven/liberty-maven-plugin/src/main/java/io/openliberty/tools/maven/server/StartDebugMojoSupport.java

Line 88 in 4ee535e

private static boolean configFilesCopied = false;

I don't see why not just make it non-static. If I am not mistaken, maven plugins are loaded in their own ClassLoader. That means as long as the plugin does not run twice in the same module at the same time with the same goal (which is unlikely for StartDebugMojoSupport), this should work.

[cherylking]

@bmarwell Thanks for looking at those. I agree that the static variable in StartDebugMojoSupport can just be made non-static.

As for the CommonLogger, I suppose I could make the logger static variable final. But the loggerImpl referenced by that static logger can change with every call to getInstance, which seems problematic to me if called from multiple threads. Maybe I am overthinking it?

[cherylking]

Just found another class that needs modifications for thread safety in ci.common. It is utilizing a lot of static variables. Not sure of the history there. Will look into changing those to non-static variables.