westonpace commented on a change in pull request #10061:
URL: https://github.com/apache/arrow/pull/10061#discussion_r616022528
##########
File path: cpp/src/arrow/util/async_generator.h
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@@ -1489,17 +1522,23 @@ class GeneratorIterator {
/// \brief Converts an AsyncGenerator<T> to an Iterator<T> by blocking until
each future
/// is finished
+///
+/// If this underlying generator transfers to the CPU pool then this blocking
call will be
+/// considered "nested parallelism" and is not safe to call from a CPU pool
thread.
+///
+/// To avoid this you can use MakeGeneratorIterator
template <typename T>
-Result<Iterator<T>> MakeGeneratorIterator(AsyncGenerator<T> source) {
- return Iterator<T>(GeneratorIterator<T>(std::move(source)));
+Result<Iterator<T>> MakeSimpleGeneratorIterator(AsyncGenerator<T> source) {
+ return Iterator<T>(SimpleGeneratorIterator<T>(std::move(source)));
}
/// \brief Adds readahead to an iterator using a background thread.
///
/// Under the hood this is converting the iterator to a generator using
/// MakeBackgroundGenerator, adding readahead to the converted generator with
/// MakeReadaheadGenerator, and then converting back to an iterator using
-/// MakeGeneratorIterator.
+/// MakeSimpleGeneratorIterator (this is safe because we the generator never
Review comment:
N/A, code removed.
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