[Rd] setting .libPaths() with parallel::clusterCall

[Mark van der Loo]

Dear all,

It is not possible to set library paths on worker nodes with
parallel::clusterCall (or snow::clusterCall) and I wonder if this is
intended behavior.

Example.

library(parallel)
libdir <- "./tmplib"
if (!dir.exists(libdir)) dir.create("./tmplib")

cl <- makeCluster(2)
clusterCall(cl, .libPaths, c(libdir, .libPaths()) )

The output is as expected with the extra libdir returned for each worker
node. However, running

clusterEvalQ(cl, .libPaths())

Shows that the library paths have not been set.

If this is indeed a bug, I'm happy to file it at bugzilla. Tested on R
4.0.3 and r-devel.

Best,
Mark
ps: a workaround is documented here:
https://www.markvanderloo.eu/yaRb/2020/12/17/how-to-set-library-path-on-a-parallel-r-cluster/


> sessionInfo()
R Under development (unstable) (2020-12-21 r79668)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 20.04.1 LTS

Matrix products: default
BLAS:   /home/mark/projects/Rdev/R-devel/lib/libRblas.so
LAPACK: /home/mark/projects/Rdev/R-devel/lib/libRlapack.so

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=nl_NL.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=nl_NL.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=nl_NL.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=nl_NL.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] parallel  stats     graphics  grDevices utils     datasets  methods
[8] base

loaded via a namespace (and not attached):
[1] compiler_4.1.0

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