[Rd] Questions/suggestions about new staged installation

Thu Apr 25 14:41:31 CEST 2019

On 4/25/19 2:20 PM, Pages, Herve wrote:
> On 4/25/19 04:57, Tomas Kalibera wrote:
>
>> On 4/25/19 3:11 AM, Pages, Herve wrote:
>>> Hi,
>>>
>>> I was playing around with inotifywait (great tool!) to see the new
>>> staged installation of source packages in action. In one terminal I'm
>>> monitoring the create/delete/move events of the installation library
>>> with:
>>>
>>>      inotifywait -m --timefmt '%F %T' --format '%T -- %w %e %f' -e create
>>> -e delete -e move path/to/R/library/
>>>
>>> While in another terminal I install CRAN package abc with:
>>>
>>>      R CMD INSTALL abc_2.1.tar.gz
>>>
>>> All deps are already installed.
>>>
>>> ## With R 3.5
>>>
>>> When installing abc the first time with R 3.5 inotifywait reports the
>>> following events:
>>>
>>> 2019-04-24 16:57:42 -- /home/hpages/R/R-3.5.r75051/library/ CREATE,ISDIR
>>> 00LOCK-abc
>>> 2019-04-24 16:57:42 -- /home/hpages/R/R-3.5.r75051/library/
>>> CREATE,ISDIR abc
>>> 2019-04-24 16:57:45 -- /home/hpages/R/R-3.5.r75051/library/ DELETE,ISDIR
>>> 00LOCK-
>>>
>>> Then on subsequent times:
>>>
>>> 2019-04-24 16:58:14 -- /home/hpages/R/R-3.5.r75051/library/ CREATE,ISDIR
>>> 00LOCK-abc
>>> 2019-04-24 16:58:14 -- /home/hpages/R/R-3.5.r75051/library/
>>> MOVED_FROM,ISDIR abc
>>> 2019-04-24 16:58:14 -- /home/hpages/R/R-3.5.r75051/library/
>>> CREATE,ISDIR abc
>>> 2019-04-24 16:58:17 -- /home/hpages/R/R-3.5.r75051/library/ DELETE,ISDIR
>>> 00LOCK-abc
>>>
>>> IIUC the additional 'MOVED_FROM,ISDIR abc'  event on subsequent installs
>>> is triggered by the backing up of the earlier installation in case the
>>> new installation fails.
>>>
>>> ## With R 3.6
>>>
>>> First installation:
>>>
>>> 2019-04-24 17:09:04 -- /home/hpages/R/R-3.6.r76385/library/ CREATE,ISDIR
>>> 00LOCK-abc
>>> 2019-04-24 17:09:04 -- /home/hpages/R/R-3.6.r76385/library/
>>> CREATE,ISDIR abc
>>> 2019-04-24 17:09:08 -- /home/hpages/R/R-3.6.r76385/library/
>>> MOVED_TO,ISDIR abc
>>> 2019-04-24 17:09:09 -- /home/hpages/R/R-3.6.r76385/library/ DELETE,ISDIR
>>> 00LOCK-abc
>>>
>>> Subsequent installations:
>>>
>>> 2019-04-24 17:09:59 -- /home/hpages/R/R-3.6.r76385/library/ CREATE,ISDIR
>>> 00LOCK-abc
>>> 2019-04-24 17:09:59 -- /home/hpages/R/R-3.6.r76385/library/
>>> MOVED_FROM,ISDIR abc
>>> 2019-04-24 17:09:59 -- /home/hpages/R/R-3.6.r76385/library/
>>> CREATE,ISDIR abc
>>> 2019-04-24 17:10:02 -- /home/hpages/R/R-3.6.r76385/library/
>>> MOVED_TO,ISDIR abc
>>> 2019-04-24 17:10:03 -- /home/hpages/R/R-3.6.r76385/library/ DELETE,ISDIR
>>> 00LOCK-abc
>>>
>>> IIUC the new 'MOVED_TO,ISDIR abc' event is triggered by the package
>>> installation folder being moved from the temporary location to the final
>>> location.
>>>
>>> However I wonder about the CREATE,ISDIR abc event. It looks like even
>>> for a staged installation tools:::.install_packages() still creates the
>>> empty abc dir. This should no longer be necessary because this empty
>>> folder is replaced later by the 'MOVED_TO,ISDIR abc' event. Am I missing
>>> somethin
>> Yes, the final directory location gets created before the
>> installation. I did this to minimize the added cognitive complexity to
>> the code. I could explore if this could be changed, if the
>> installation could work without that directory (which would mean
>> implementing and testing on all CRAN/BIOC, installing in different
>> modes, so certainly some effort).  Is the current implementation
>> causing any problem?
>>
>>> Another thing: the times indicate that the 'MOVED_TO,ISDIR abc' event
>>> (move from temp to final location) happens about 3-4 seconds after the
>>> 'MOVED_FROM,ISDIR abc' event (backing up). In this interval of time, the
>>> abc package is missing. Wouldn't it be safer to leave the earlier
>>> installation where it is and to replace it when the new installation
>>> folder is moved from the temporary location to the final location? Said
>>> otherwise, the backing up step no longer seems necessary with staged
>>> installs. So inotifywait would report something like this:
>>>
>>> 2019-04-24 17:09:59 -- /home/hpages/R/R-3.6.r76385/library/ CREATE,ISDIR
>>> 00LOCK-abc
>>> 2019-04-24 17:10:02 -- /home/hpages/R/R-3.6.r76385/library/
>>> MOVED_TO,ISDIR abc
>>> 2019-04-24 17:10:03 -- /home/hpages/R/R-3.6.r76385/library/ DELETE,ISDIR
>>> 00LOCK-abc
>>>
>>> That is, only 3 events. On first and subsequent installation.
>> I don't think that would be possible. The package is test-loaded also
>> from the final installation directory, and if that fails, restored
>> from a back-up. This test-loading is useful as it can detect some
>> problems with hard-coded directories possibly not detected before on
>> test-loading from the temporary installation directory.
> Makes sense.
>
> So backing up is still needed.
>
> But couldn't the gap of 3-4 seconds where the abc package is missing be
> reduced by backing up right before moving the newly installed package
> from the temporary location to the final location?
>
> In other words, instead of:
>
>       back up, then install to temp loc, then move to final loc
>
> do:
>
>       install to temp loc, then back up, then move to final loc
>
> This would reduce the gap to almost 0 seconds on a Unix file system
> where moving a folder is very cheap (even if the folder is big), at
> least when moving doesn't cross partition borders.
>
> Not a big deal for a light package like abc but some Bioconductor
> packages take about 20 min. to compile!

It should be possible, probably. But why is the gap a problem? And why 
is a shorter gap better than long gap? (the time depends on how long it 
takes to load the package, which can be >10s for some Bioconductor 
packages).

It is not safe to run concurrently with the installation any code on the 
same library that would be accessing the packages being installed. Such 
code could access the old version of the package mixed with the new 
version. A longer gap could actually (perhaps accidentally but still) 
make such problems more visible, and easier to detect, than a short gap.

Tomas

>
> Thanks,
>
> H.
>
>
>>
>> Best,
>> Tomas
>>
>>> Cheers,
>>>
>>> H.
>>>
>>>
>>>    > sessionInfo()
>>> R version 3.6.0 beta (2019-04-12 r76385)
>>> Platform: x86_64-pc-linux-gnu (64-bit)
>>> Running under: Ubuntu 16.04.5 LTS
>>>
>>> Matrix products: default
>>> BLAS:   /home/hpages/R/R-3.6.r76385/lib/libRblas.so
>>> LAPACK: /home/hpages/R/R-3.6.r76385/lib/libRlapack.so
>>>
>>> locale:
>>>     [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>>>     [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
>>>     [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
>>>     [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
>>>     [9] LC_ADDRESS=C               LC_TELEPHONE=C
>>> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>>>
>>> attached base packages:
>>> [1] stats     graphics  grDevices utils     datasets  methods base
>>>
>>> loaded via a namespace (and not attached):
>>> [1] compiler_3.6.0
>>>
>>>