Tue, 31 Oct 2023

RcppArmadillo on CRAN: Bugfix, Thread Throttling

armadillo image

Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language–and is widely used by (currently) 1110 other packages on CRAN, downloaded 31.2 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 563 times according to Google Scholar.

This release brings upstream bugfix releases 12.6.5 (sparse matrix corner case) and 12.6.6 with an ARPACK correction. Conrad released it this this morning, I had been running reverse dependency checks anyway and knew we were in good shape so for once I did not await a full run against the now over 1100 (!!) packages using RcppArmadillo.

This release also contains a change I prepared on Sunday and which helps with much-criticized (and rightly I may add) insistence by CRAN concerning ‘throttling’. The motivation is understandable: CRAN tests many packages at once on beefy servers and can ill afford tests going off and requesting numerous cores. But rather than providing a global setting at their end, CRAN insists that each package (!!) deals with this. The recent traffic on the helpful-as-ever r-pkg-devel mailing clearly shows that this confuses quite a few package developers. Some have admitted to simply turning examples and tests off: a net loss for all of us. Now, Armadillo defaults to using up to eight cores (which is enough to upset CRAN) when running with OpenMP (which is generally only on Linux for “reasons” I rather not get into…). With this release I expose a helper functions (from OpenMP) to limit this. I also set up an example package and repo RcppArmadilloOpenMPEx detailing this, and added a demonstration of how to use the new throttlers to the fastLm example. I hope this proves useful to users of the package.

The set of changes since the last CRAN release follows.

Changes in RcppArmadillo version (2023-10-31)

  • Upgraded to Armadillo release 12.6.6 (Cortisol Retox)

    • Fix eigs_sym(), eigs_gen() and svds() to generate deterministic results in ARPACK mode
  • Add helper functions to set and get the number of OpenMP threads

  • Store initial thread count at package load and use in thread-throttling helper (and resetter) suitable for CRAN constraints

Changes in RcppArmadillo version (2023-10-14)

  • Upgraded to Armadillo release 12.6.5 (Cortisol Retox)

    • Fix for corner-case bug in handling sparse matrices with no non-zero elements

Courtesy of my CRANberries, there is a diffstat report relative to previous release. More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the Rcpp R-Forge page.

If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

/code/rcpp | permanent link