[R-pkg-devel] Winbuilder 'experimental' toolchain 4-5x slower than all other architectures

[Dirk Eddelbuettel]

On 5 February 2020 at 08:39, Brian G. Peterson wrote:
| We've noticed over the past week that Winbuilder/R-Hub's 'experimental'

Are you refering to winbuilder, or to rhub?

| Rtools4 toolchain images for Windows are approximately 4-5x slower than
| all other containers to build and check several packages we maintain.

That made me curious and I just did a quick run at rhub comparing windows
builds of r-devel (ie "old" toolchain) and r-devel using the new tools4. 

AFAICT the difference is due to more prebuilt packages coming in for the
former, and more packages building from source for the latter.

I used a small package with few depends---but critically with the
knitr/rmarkdown stack which leads to stringi building from source building
libicu first. That alone will set up back a good couple of minutes.  FWIW I
ended up with 4 minutes for the old tools versus 24 minutes with rtools4.

But as a cross-check, I used an even smaller package with no depends. And
there the time difference was neglible and both took about 3 minutes.

So I would recommend to try calling rhub _on that platform_ with the added

   check_args="--no-manual --no-vignettes"

argument so suppress vignette and manual builds and tests. I think that may
help you with shorter setup times.
 
| This affects everything, including example timings, where this
| architecture is the only architecture that shows any example run-times
| over 5 seconds. (including Windows under the older toolchain).
| 
| Does CRAN expect us to optimize our code for the clearly non-performant 
| 'experimental' Windows toolchain?
| 
| I'd like to send a new version of our package PerformanceAnalytics to
| CRAN, but the Windows experimental toolchain is preventing a 100% clean
| set of checks.

I think CRAN is fairly reasonable and lenient about run-time of examples, and
the local check time. Could you possibly demonstrate an actual slowdown in
example timings? If there is one, I am sure Jeroen would like to know more.

Dirk

-- 
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