Howdy, Thank you very much, the reproducer works. Did not dig thru it fully, but here are some related issues:
https://issues.apache.org/jira/browse/MNG-8028 (funny thing, I created this few weeks ago) https://issues.apache.org/jira/browse/MNG-6300 Will report back tomorrow (EU TZ) T On Wed, Feb 7, 2024 at 7:48 PM Joseph Leonard < joseph.leon...@alfasystems.com> wrote: > Hi Tamás, > I have created a simple example here: > https://github.com/josple/mvn-multibuild-issue > Hopefully the README is clear enough – let me know if I can clarify > anything. > Thanks, > Joe > > On 2024/02/07 17:33:08 Tamás Cservenák wrote: > > Howdy, > > > > In that case, there is something fishy with the project, my blind guess > > would be some "hidden" inter-module dependency maybe? > > > > Can you provide access to source, or, if not feasible, could you provide > > some reproducer and publish it on Github/Gitlab/whatever (maybe even just > > send it privately as ML strips off attachments and images) for us to see > > this in action? > > > > Thanks > > T > > > > On Wed, Feb 7, 2024 at 6:29 PM Joseph Leonard < > > joseph.leon...@alfasystems.com> wrote: > > > > > Hi Tamás, > > > We have previously played around a bit with mvnd but not takari > directly – > > > I will have a play with it. With regards to this issue, using the > takari > > > smart builder unfortunately doesn’t resolve the issue. > > > Joe > > > > > > On 2024/02/07 11:41:22 Tamás Cservenák wrote: > > > > Can you please try smart builder instead? > > > > https://github.com/takari/takari-smart-builder > > > > > > > > (note: smart builder is used by mvnd as well) > > > > > > > > The difference between the two can be seen here: > > > > http://takari.io/book/30-team-maven.html#takari-smart-builder > > > > > > > > On Wed, Feb 7, 2024 at 11:50 AM Joseph Leonard < > > > > joseph.leon...@alfasystems.com> wrote: > > > > > > > > > Hi Tamás, > > > > > Yeah, this was unexpected to me initially as well. From what I can > tell > > > > > the Maven reactor only considers direct dependencies (i.e. not > > > transitive > > > > > dependencies) between the modules in the reactor when working out > the > > > build > > > > > graph. For example if you have a simple linear dependency chain of: > > > > > One --> Two --> Three --> Four --> Five > > > > > Then invoking “mvn clean verify -pl One,Two,Four,Five -T 2 will > result > > > in > > > > > two ‘graphs’ being built in parallel ([One,Two] and [Four,Five]). I > > > assume > > > > > this is as designed because it actually offers quite powerful > > > functionality > > > > > to improve the parallelism in your build. An example of where this > is > > > legit > > > > > is when: > > > > > > > > > > * “Four” has a test scope dependency on “Five” > > > > > * “One” has a test scoped dependency on “Two” > > > > > If you made a src code change to “Five” and “Two” then it would be > > > safe to > > > > > build [One,Two] and [Four,Five] in parallel because you know the > > > changes > > > > > within these graphs cannot impact each other. > > > > > Joe > > > > > > > > > > On 2024/02/06 21:37:42 Tamás Cservenák wrote: > > > > > > Howdy, > > > > > > > > > > > > To me this looks like Maven is not aware that the App depends on > > > > > ModuleB... > > > > > > Are they "plain dependency" linked? Or what kind of dependency we > > > talk > > > > > > about here? > > > > > > In short: why would App start while ModuleB (upstream dep) is not > > > done? > > > > > > Something is fishy here. > > > > > > > > > > > > T > > > > > > > > > > > > > > > > > > On Tue, Feb 6, 2024 at 11:40 AM Joseph Leonard < > > > > > > joseph.leon...@alfasystems.com> wrote: > > > > > > > > > > > > > Hi all, > > > > > > > > > > > > > > It would be great to get any thoughts on whether the following > is a > > > > > defect: > > > > > > > > > > > > > > > > > > > > > Issue details: > > > > > > > tl;dr > > > > > > > > > > > > > > Maven can resolve dependencies either from: > > > > > > > > > > > > > > * an external repo > > > > > > > * a class directory of a module being built within the > reactor > > > > > > > * a packaged jar of a module being built within the reactor > > > > > > > > > > > > > > If you run a concurrent multi-module build it is possible to > get a > > > race > > > > > > > condition whereby the build of module Foo may resolve module > Bar > > > from > > > > > > > either of the three resolution channels. This inconsistency can > > > result > > > > > in > > > > > > > the Maven war plugin sometimes failing to build a functional > war > > > file. > > > > > I > > > > > > > would expect a consistent resolution would always take place. > > > > > > > > > > > > > > Full details > > > > > > > Scenario > > > > > > > > > > > > > > Consider you have a repo with the following structure: > > > > > > > > > > > > > > App > > > > > > > > > > > > > > / \ > > > > > > > > > > > > > > / \ > > > > > > > > > > > > > > (compile scope) (test scope) > > > > > > > > > > > > > > / \ > > > > > > > > > > > > > > \/_ _\/ > > > > > > > > > > > > > > ModuleA TestSupportModule1 > > > > > > > > > > > > > > / > > > > > > > > > > > > > > / > > > > > > > > > > > > > > (compile scope) > > > > > > > > > > > > > > / > > > > > > > > > > > > > > \/_ > > > > > > > > > > > > > > ModuleB > > > > > > > > > > > > > > / > > > > > > > > > > > > > > / > > > > > > > > > > > > > > (test scope) > > > > > > > > > > > > > > / > > > > > > > > > > > > > > \/_ > > > > > > > > > > > > > > TestSupportModule2 > > > > > > > > > > > > > > If you were to make a src code change to the following test > support > > > > > > > modules: > > > > > > > > > > > > > > * TestSupportModule1 > > > > > > > * TestSupportModule2 > > > > > > > > > > > > > > Then the minimum number of modules we need to build to verify > the > > > > > change > > > > > > > set is OK is: > > > > > > > > > > > > > > * TestSupportModule1 > > > > > > > * TestSupportModule2 > > > > > > > * ModuleB > > > > > > > * App > > > > > > > > > > > > > > i.e. there is no requirement to build ModuleA because we know > that > > > > > none of > > > > > > > the src code changes could impact the classpaths used in its > maven > > > > > build. > > > > > > > > > > > > > > We know that despite 'App' depending (transitively) on ModuleB > > > there > > > > > is no > > > > > > > need for the 'App' build to wait for ModuleB to complete its > build > > > > > because > > > > > > > the src code change to TestSupportModule2 will not impact any > of > > > the > > > > > > > classpaths used in the App maven build. Therefore to get the > most > > > > > efficient > > > > > > > build possible we ideally would invoke Maven to run with 2 > threads > > > and > > > > > with > > > > > > > instruction to build two distinct 'dependency graphs': > > > > > > > > > > > > > > * TestSupportModule1 followed by ModuleB > > > > > > > * TestSupportModule1 followed by App > > > > > > > > > > > > > > The following Maven command achieves exactly what we want > because > > > the > > > > > > > reactor build order is based only on the direct (i.e. > > > non-transitive) > > > > > > > dependencies of the modules provided to the reactor in the > build > > > > > command. > > > > > > > Therefore the absence of ModuleA results in two distinct > > > 'dependency > > > > > > > graphs': > > > > > > > > > > > > > > mvn clean verify -pl > > > TestSupportModule1,TestSupportModule2,ModuleB,App > > > > > -T 2 > > > > > > > > > > > > > > Note: In reality the code base I maintain has a very large > > > monobuild > > > > > with > > > > > > > 100s of modules and this type of build optimisation makes a > > > significant > > > > > > > difference to the speed of our monobuild (we use > > > > > > > > > > > > > > > > https://github.com/gitflow-incremental-builder/gitflow-incremental-builder > > > > > > > to automate the logic of determining which modules to include > in > > > the > > > > > > > reactor based on our change set). > > > > > > > > > > > > > > Issue > > > > > > > > > > > > > > We have encountered an issue in the above scenario because the > > > 'App' > > > > > build > > > > > > > has a race condition with the ModuleB build which will result > in > > > one > > > > > of the > > > > > > > following three outcomes: > > > > > > > > > > > > > > * If the 'App' build starts before the ModuleB build has > > > compiled > > > > > its > > > > > > > src classes then the 'App' build will resolve ModuleB from the > > > external > > > > > > > repo (i.e. equivalent to ModuleB not being in the reactor at > all) > > > > > > > * If the 'App' build starts after ModuleB has compiled its > src > > > > > classes > > > > > > > but before it has packaged these classes into a jar then the > 'App' > > > > > build > > > > > > > will resolve ModuleB's target/classes directory > > > > > > > * If the 'App' build starts after ModuleB has packaged its > jar > > > file > > > > > > > then the 'App' build will resolve ModuleB's target/ModuleB.jar > > > file. > > > > > > > > > > > > > > In many scenarios this dependency resolution inconsistency > doesn't > > > > > > > represent a challenge. However, it does cause an issue in our > case > > > > > because > > > > > > > the 'App' POM has its Maven packaging stanza configured to war > and > > > in > > > > > the > > > > > > > scenario where ModuleB's target/classes directory is resolved > by > > > the > > > > > 'App' > > > > > > > then this results in the resultant 'App' war file being > packaged > > > with a > > > > > > > completely empty ModuleB.jar file. > > > > > > > > > > > > > > Proposed solution > > > > > > > > > > > > > > Ideally we would like the Maven reactor to retain isolation > > > between the > > > > > > > two distinct 'dependency graphs' it constructs at instantiation > > > > > throughout > > > > > > > the entire Maven build. This would mean, in the simple example > > > above, > > > > > that > > > > > > > the 'App' would always resolves ModuleB from the external repo > > > > > (regardless > > > > > > > of whether the reactor has built ModuleB or not in a separate > > > > > 'dependency > > > > > > > graph' in the reactor). > > > > > > > > > > > > > > > > > > > > > > > > > > > > Joseph Leonard > > > > > > > Manager > > > > > > > > > > > > > > Alfa > > > > > > > ________________________________ > > > > > > > e: joseph.leon...@alfasystems.com | w: alfasystems.com< > > > > > > > https://www.alfasystems.com> > > > > > > > t: +44 (0)20 7588 1800 | Moor Place, 1 Fore Street Avenue, > London, > > > EC2Y > > > > > > > 9DT, GB > > > > > > > ________________________________ > > > > > > > > > > > > > > The contents of this communication are not intended to be > binding > > > or > > > > > > > constitute any form of offer or acceptance or give rise to any > > > legal > > > > > > > obligations on behalf of the sender or Alfa. 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