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From Ralph Goers <>
Subject Re: 2.0.10 performance.....
Date Thu, 21 Aug 2008 17:11:34 GMT
I'm still wondering if given the impact this has shouldn't it be pulled 
from 2.0.x and moved into 2.1?  In my view the purpose of 2.1.x is it 
lock down 2.0.x to bug fixes that don't introduce new behaviors. 

John Casey wrote:
> So, I've been working on the hotspots (late last night and again this 
> morning) trying to see what improvements I could make. In the end, I 
> was able to improve things a bit in terms of interpolation efficiency 
> and model cloning (turned out that was a big time sink too). However, 
> in the end I think the sheer number of transitions between concrete 
> and dynamic state are just crushing the life out of this.
> I talked briefly with you, Dan, yesterday about detecting whether some 
> key parts of the project/model graph had changed, and using those to 
> trigger a concrete -> dynamic transition...otherwise, leaving the 
> project in concrete mode until such a trigger trips. Thinking about 
> this more, I think we could easily cover 90% of use cases with this 
> approach, right off the bat. From that point, we could probably hone 
> the detection system over time to pick up on anything we missed. I 
> think this has a lot of potential to improve the performance numbers, 
> and it's something I've just started to pursue here.
> I'm not wild about adding the new annotation for now, simply because 
> of the time and pain involved in bringing all of the affected plugins 
> up to snuff (they'd have to have new releases as well). As for 
> detecting project-state changes in the plugin itself (or the POM, as 
> Brian asked about) we'd have to scan the entire logic of the mojo (and 
> classes it used) to see whether any of it modified the project/model 
> graph...which is obviously waaaay too heavy to do at runtime.
> Additionally, as for adding a command-line option: this would 
> definitely work, but it would be putting the onus on the user to adapt 
> to our deficient design. It would inevitably increase the confusion 
> around the use of Maven ("When do I use the dynamic flag, when can I 
> skip it...why should I care?") and in any case I'm concerned about 
> building up more legacy to support in things like that, once we find a 
> real solution to the problem.
> For now, I'm going to look more closely into these trigger values. 
> Please let me know if you have any ideas...
> Thanks,
> -john
> Daniel Kulp wrote:
>> The latest stuff on John's branch is "better", but it's still about 
>> 4x - 5x slower for some of the actions I do several times a day.   
>> I'd estimate that I'd end up wasting 20-30 minutes a day waiting for 
>> it compared to 2.0.9.  I find that unacceptable and wouldn't be able 
>> to recommend it get rolled out to other developers.   I couldn't 
>> "cost justify" reducing the productivity of everyone.
>> However, the dynamic re-interpretation stuff is needed due to a few 
>> plugins doing some strange things.  (clover, cobertura, etc...)   The 
>> problem is that it causes a major slowdown for ALL plugins, even the 
>> "well behaved" plugins.
>> My suggestion would be:
>> 1) Leave the reinterpret code in, but turn it off by default.   Add a 
>> command line flag or system property to turn it on in the cases that 
>> it's needed.   The default behavior would be no worse than 2.0.9.
>> 2) Extend the plugin model to add a "@modifiesBuildEnvironment" or 
>> something similar so a plugin can let the execution environment know 
>> that special care will need to be taken after this plugin runs.   
>> Once that is in place, future versions of the affected plugins could 
>> set that to make sure things work correctly.
>> Thoughts?

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