ARROW-17252: [R] Intermittent valgrind failure (wait for thread pool approach)

r/R/arrow-package.R

@@ -81,6 +81,14 @@
   invisible()
 }
 
+.onUnload <- function(...) {
+  # When running valgrind we need to wait for the thread pools to finish
+  # running background tasks or else spurious memory leaks may be reported.
+  if (on_linux_dev()) {
+    WaitForIdleThreadPool()
+  }
+}
+
 configure_tzdb <- function() {
   # This is needed on Windows to support timezone-aware calculations
   if (requireNamespace("tzdb", quietly = TRUE)) {

r/src/threadpool.cpp

@@ -54,3 +54,17 @@ int GetIOThreadPoolCapacity() { return arrow::io::GetIOThreadPoolCapacity(); }
 void SetIOThreadPoolCapacity(int threads) {
   StopIfNotOk(arrow::io::SetIOThreadPoolCapacity(threads));
 }
+
+namespace arrow {
+namespace io {
+namespace internal {
+arrow::internal::ThreadPool* GetIOThreadPool();
+}
+}  // namespace io
+}  // namespace arrow
+
+// [[arrow::export]]
+void WaitForIdleThreadPool() {
+  arrow::internal::GetCpuThreadPool()->WaitForIdle();
+  arrow::io::internal::GetIOThreadPool()->WaitForIdle();
+}