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re-export tbbmalloc from RcppParallel.dll on windows #262

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kevinushey merged 3 commits into from
Jul 24, 2026
Merged

re-export tbbmalloc from RcppParallel.dll on windows #262

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9df8885
re-export tbbmalloc from RcppParallel.dll on windows
kevinushey Jul 24, 2026
aa84a57
add test for downstream use of the scalable allocator
kevinushey Jul 24, 2026
91fa770
clear R_TESTS when building the test package
kevinushey Jul 24, 2026
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add test for downstream use of the scalable allocator 
generates a small package using scalable_malloc and scalable_free via
the RcppParallel::CxxFlags() / RcppParallelLibs() flags, installs it,
and confirms the allocator can be used. on windows, this exercises the
tbbmalloc re-export from RcppParallel.dll; elsewhere, the run-time
resolution of tbbmalloc symbols loaded by RcppParallel::.onLoad().

the test builds a package, so it runs only on CI (or with NOT_CRAN),
and only when the tbb backend is enabled.
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@kevinushey
kevinushey committed Jul 24, 2026
commit aa84a5744f46422dd2d15666d70b700372a08146
106 changes: 106 additions & 0 deletions tests/scalable-allocator.R
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# Check that packages using TBB's scalable allocator can be compiled, linked,
# and loaded against this installation of RcppParallel.
#
# On Windows, downstream packages link only '-lRcppParallel', and so this
# requires RcppParallel.dll to re-export the tbbmalloc API on their behalf.
# On other platforms, the symbols are left undefined at link time, and
# resolved from the tbbmalloc library loaded when RcppParallel is loaded.
#
# https://github.com/RcppCore/RcppParallel/pull/262

library(RcppParallel)

# building the test package requires a toolchain, so keep this test
# off of CRAN's machines
ci <- nzchar(Sys.getenv("CI")) || identical(Sys.getenv("NOT_CRAN"), "true")
if (!ci) {
writeLines("Not running on CI; skipping scalable allocator test.")
quit(save = "no")
}

# the scalable allocator is only available with the TBB backend
if (!RcppParallel:::TBB_ENABLED) {
writeLines("TBB is not enabled; skipping scalable allocator test.")
quit(save = "no")
}

# generate the test package
pkgRoot <- file.path(tempdir(), "scalabletest")
dir.create(file.path(pkgRoot, "src"), recursive = TRUE, showWarnings = FALSE)

writeLines(con = file.path(pkgRoot, "DESCRIPTION"), c(
"Package: scalabletest",
"Type: Package",
"Title: Test Linking to the TBB Scalable Allocator",
"Version: 0.1.0",
"Author: RcppParallel Authors",
"Maintainer: RcppParallel Authors <noreply@example.com>",
"Description: Confirms that packages can use the TBB scalable allocator.",
"License: GPL-2",
"Imports: RcppParallel"
))

writeLines(con = file.path(pkgRoot, "NAMESPACE"), c(
"useDynLib(scalabletest)",
"importFrom(RcppParallel, RcppParallelLibs)"
))

writeLines(con = file.path(pkgRoot, "src", "Makevars"), c(
'PKG_CXXFLAGS = $(shell "${R_HOME}/bin/Rscript" -e "RcppParallel::CxxFlags()")',
'PKG_LIBS = $(shell "${R_HOME}/bin/Rscript" -e "RcppParallel::RcppParallelLibs()")'
))

writeLines(con = file.path(pkgRoot, "src", "Makevars.win"), c(
'PKG_CXXFLAGS = $(shell "${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" -e "RcppParallel::CxxFlags()")',
'PKG_LIBS = $(shell "${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" -e "RcppParallel::RcppParallelLibs()")'
))

writeLines(con = file.path(pkgRoot, "src", "scalable.cpp"), c(
"#include <tbb/scalable_allocator.h>",
"",
"#include <R.h>",
"#include <Rinternals.h>",
"",
'extern "C" SEXP scalable_roundtrip(SEXP sizeSEXP)',
"{",
" int size = Rf_asInteger(sizeSEXP);",
"",
" double* data = (double*) scalable_malloc(size * sizeof(double));",
" if (data == NULL)",
" return Rf_ScalarLogical(FALSE);",
"",
" for (int i = 0; i < size; i++)",
" data[i] = i;",
"",
" double total = 0.0;",
" for (int i = 0; i < size; i++)",
" total += data[i];",
"",
" scalable_free(data);",
"",
" double expected = (double) size * (size - 1) / 2;",
" return Rf_ScalarLogical(total == expected);",
"}"
))

# install it, making sure child processes resolve this RcppParallel
libDir <- file.path(tempdir(), "library")
dir.create(libDir, recursive = TRUE, showWarnings = FALSE)
Sys.setenv(R_LIBS = paste(.libPaths(), collapse = .Platform$path.sep))

rExe <- file.path(R.home("bin"), if (.Platform$OS.type == "windows") "R.exe" else "R")
args <- c("CMD", "INSTALL", "--no-multiarch", paste0("--library=", shQuote(libDir)), shQuote(pkgRoot))

output <- suppressWarnings(system2(rExe, args, stdout = TRUE, stderr = TRUE))
writeLines(output)

status <- attr(output, "status")
if (is.numeric(status) && status != 0L)
stop("error installing test package (status code ", status, ")")

# load it, and check that the scalable allocator can be used
invisible(loadNamespace("scalabletest", lib.loc = libDir))
ok <- .Call("scalable_roundtrip", 1000L, PACKAGE = "scalabletest")
writeLines(paste("scalable allocator round trip:", if (isTRUE(ok)) "OK" else "FAILED"))
stopifnot(isTRUE(ok))
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