[R-pkg-devel] Issue with CPU time > 2.5 times elapsed time

[Jan van der Laan]

I am trying to upload a new version of the reclin2 package, but it fails 
the pre-tests on Debian with the following message:

 > * checking examples ... [14s/4s] NOTE
 > Examples with CPU time > 2.5 times elapsed time
 >                   user system elapsed ratio
 > select_threshold 3.700  0.122   0.455 8.400
 > select_n_to_m    4.228  0.180   0.623 7.075
 > * checking for unstated dependencies in ‘tests’ ... OK

See
https://win-builder.r-project.org/incoming_pretest/reclin2_0.3.1_20230716_124651/Debian/00check.log 
for the complete output.

I can't see why this happens and I can't seem to reproduce this on my 
machine. The examples do call makeCluster from parallel, but only start 
one thread. The code that is ran in the examples only call base-r 
functions and data.table functions. I can imagine data.table starting 
multiple threads. However the example consists only of 17 records; and 
data.table should not use more than two threads on that system anyway. 
So I don't see where the large difference between the two is coming 
from. Does anyone have a clue?

The code is here: https://github.com/djvanderlaan/reclin2 one of the 
examples that fails is here: 
https://github.com/djvanderlaan/reclin2/blob/master/R/select_threshold.R#L21. 


Thanks.
Jan