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Re: [m2e-users] m2e hanging at 65% (aka Aether locking)

Main question here: As M2E is obviously building the project model
anyways, and internally (for example to maintain, and display the list
of "Maven Dependencies"), is it really necessary to rebuild that?


On Wed, Oct 7, 2015 at 1:28 PM, Andi Scharfstein
<andi.scharfstein@xxxxxxxxxx> wrote:
> Hello,
> we recently introduced m2e for a big legacy system and now are trying to
> deal with one issue - it is very slow when running unit tests, which we
> don't see on the command line with "mvn test". I'm asking here for help as
> a last resort, we already tried various approaches but none so far worked.
>
> This is the scenario:
> We are working on a legacy system distributed over ~300 Eclipse projects,
> where there are obviously quite a few dependencies. I now want to run a
> specific test case in one of the projects, this project has about 45
> dependencies overall (even split between JAR dependencies and project
> dependencies). Before the test case starts running, m2e spends about 13
> seconds hanging at 65% ("Launching"), after that the test is executed as
> expected. We are using Eclipse 4.4.2 and m2e 1.6.1.20150625-2338, but we
> already tried other releases and the behavior remained consistent. Our
> machines are running Windows 7 (64bit).
>
> Profiling Eclipse showed that of the 13 seconds we spent waiting, almost
> all of the time was taken up by various calls to
> org.apache.maven.project.DefaultProjectBuilder.build(), going to
> DefaultProjectBuilder.resolveDependencies() and
> DefaultProjectBuilder.initProject() which again uses
> resolveDependencies(). In these calls, over 90% of the time was spent just
> for io.takari.aether.concurrency.LockingSyncContext to acquire and close
> locks. I have observed hundreds of these AETHERLOCK files being created
> and deleted again in my Maven repo (which resides on an SSD by the way).
>
> So, I have a number of questions:
> - Why does locking take so much time?
> - Why is this behavior only visible using m2e, but not pure Maven?
> - And most importantly, how do I make it go away?
>
> I would be most grateful for any answers, suggestions or debugging advice.
> Naturally I'll gladly answer any clarification questions. I hope this is
> the right forum for this questions, please feel free to redirect me to
> some other place if that assumption turns out to be misguided.
>
> Thanks in advance
> Andi Scharfstein
>
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