paleolimbot commented on code in PR #12558:
URL: https://github.com/apache/arrow/pull/12558#discussion_r843910759
##########
r/R/arrow-package.R:
##########
@@ -31,6 +31,11 @@
#' @importFrom vctrs s3_register vec_size vec_cast vec_unique
.onLoad <- function(...) {
+ if (arrow_available()) {
+ # Make sure C++ knows on which thread it is safe to call the R API
+ InitializeMainRThread()
Review Comment:
I asked in the r-lib slack channel and nobody seems to feel that this will
be a problem. They did advise to check `parallel::mclapply()` since this
creates a fork of the process, but a check seems to indicate that the value of
`std::this_thread::get_id()` seems to be stable if somebody does happen to do
that:
``` r
cpp11::cpp_source(code = '
#include "cpp11.hpp"
#include <thread>
#include <sstream>
[[cpp11::register]]
std::string thread_id() {
std::thread::id id = std::this_thread::get_id();
std::stringstream ss;
ss << id;
return ss.str();
}
')
thread_id()
#> [1] "0x100e33d40"
unique(lapply(1:1e3, function(x) thread_id()))
#> [[1]]
#> [1] "0x100e33d40"
unique(parallel::mclapply(1:1e3, function(x) thread_id(), mc.cores = 8))
#> [[1]]
#> [1] "0x100e33d40"
```
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