Re: [tycho-dev] Fwd: [Bug 356888] Build performance drop with Tycho 0.13

[Igor Fedorenko <igor@xxxxxxxxxxxxxx>]

I ran some tests on m2e-core build (20 modules, uses implicit target
platform). On my hardware, P2TargetPlatformResolver.resolvePlatform
takes roughly 17 seconds, or ~0.85 seconds per module. This is roughly
inline with numbers I remember from profiling jbosstools build couple of
years ago.

For the project mentioned in the first comment of 356888, going from
0.12 to 0.13 resulted in ~3.9 seconds build time *increase* per module.
Even if we assume target platform resolution did not take any time using
Tycho 0.12 for that project, we are still talking about >4x longer
resolution times compared to m2e-core.

My point is, resolution time increase may or may not be explained by the
"proper" use of slicer+projector in .target resolution. I believe it is
important to understand what happened before we attempt to mask the
problem by caching resolved .target files.

--
Regards,
Igor

On 11-10-05 10:44 AM, Oberlies, Tobias wrote:
> This is correct: both the "calculation of the implicit target
> platform" (which I prefer to simply call "dependency resolution") and
> the interpretation of target definition files roughly take the same
> time. The difference to 0.12.0 however is that target file
> interpretation and dependency resolution are done in two separate
> slicer+projector calls. The reason is that only then it is possible
> to get a "correct", Eclipse-like interpretation of target files.
>
> The good thing about this independent resolver calls is that the
> target file resolution always yields the same result, and hence can
> be cached - unfortunately it currently isn't the case, but this
> should be a quick win.
>
> In the mid-term, there is even another optimization that we can do:
> For eclipse-feature, eclipse-repository, and the future
> eclipse-product packaging types, we could omit the dependency
> resolution (i.e. stop after target platform computation) and this
> which would save us more slicer+projector calls, making that version
> even faster than 0.12.0. With
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=353889 done, this
> shouldn't even be hard to do, but 353889 will still take me a while.
>
> Regards
> Tobias
>
>
> > -----Original Message-----
> > From: tycho-dev-bounces@xxxxxxxxxxx [mailto:tycho-dev-bounces@xxxxxxxxxxx]
> > On Behalf Of Igor Fedorenko
> > Sent: Mittwoch, 5. Oktober 2011 15:25
> > To: Tycho developers list
> > Subject: [tycho-dev] Fwd: [Bug 356888] Build performance drop with Tycho
> > 0.13.0
> >
> > Tobias,
> >
> > Do you mind explaining the difference between the new way of
> > interpreting .target files and calculation of implicit target platform?
> >   From what I understand, in both cases Tycho invokes slicer+projector in
> > about the same way, so I assume performance should be comparable too...
> > What am I missing?
> >
> > --
> > Regards,
> > Igor
> >
> > -------- Original Message --------
> > Subject: [Bug 356888] Build performance drop with Tycho 0.13.0
> > Date: Wed,  5 Oct 2011 09:17:22 -0400
> > From: bugzilla-daemon@xxxxxxxxxxx
> > To: igor@xxxxxxxxxxxxxx
> >
> > https://bugs.eclipse.org/bugs/show_bug.cgi?id=356888
> > Product/Component: Tycho / Core
> >
> > Tobias Oberlies<tobias.oberlies@xxxxxxx>  changed:
> >
> >              What    |Removed                     |Added
> > --------------------------------------------------------------------------
> > --
> >              Platform|PC                          |All
> >               Version|unspecified                 |0.13.0
> >            OS/Version|Windows 7                   |All
> >
> > --- Comment #8 from Tobias Oberlies<tobias.oberlies@xxxxxxx>  2011-10-05
> > 09:17:18 EDT ---
> > There is one pretty obvious thing which we should fix first before
> > investigating further:
> > In Tycho 0.13.0, target definition files are (for the first time)
> > interpreted
> > correctly. This requires some potentially costly calls to p2, so the
> > build is
> > expected to take longer with 0.13.0 than with 0.12.0.
> > Still, the current implementation is unnecessarily slow: In the loop which
> > computes the target _platform_ [1] for each module, the target _definition
> > file_ is resolved over and over again. We obviously need a cache for this.
> >
> > [1] http://wiki.eclipse.org/Tycho/Glossary
> >
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