mapleFU commented on PR #38466:
URL: https://github.com/apache/arrow/pull/38466#issuecomment-1810336661
Sadly I've trigger another problem when trying to re-produce the bug. 😅
```
class DelayedBufferReader : public ::arrow::io::BufferReader {
public:
explicit DelayedBufferReader(const std::shared_ptr<::arrow::Buffer>&
buffer)
: ::arrow::io::BufferReader(buffer) {}
::arrow::Future<std::shared_ptr<Buffer>> ReadAsync(const
::arrow::io::IOContext& io_context, int64_t position,
int64_t nbytes)
override {
read_async_count.fetch_add(1);
auto self =
std::dynamic_pointer_cast<DelayedBufferReader>(shared_from_this());
return DeferNotOk(::arrow::io::internal::SubmitIO(
io_context, [self, position, nbytes, io_context] {
std::this_thread::sleep_for(std::chrono::seconds(1));
return self->::arrow::io::BufferReader::ReadAsync(io_context,
position, nbytes);
}));
}
std::atomic<int> read_async_count{0};
};
TEST_F(TestParquetFileFormat, MultithreadedScanUnsafe) {
auto reader = MakeGeneratedRecordBatch(schema({field("utf8", utf8())}),
10000, 100);
ASSERT_OK_AND_ASSIGN(auto buffer,
ParquetFormatHelper::Write(reader.get()));
for (int idx = 0; idx < 3; ++idx) {
auto buffer_reader = std::make_shared<DelayedBufferReader>(buffer);
auto source = std::make_shared<FileSource>(buffer_reader,
buffer->size());
auto fragment = MakeFragment(*source);
std::shared_ptr<Scanner> scanner;
{
auto options = std::make_shared<ScanOptions>();
auto fragment_scan_options =
std::make_shared<ParquetFragmentScanOptions>();
fragment_scan_options->arrow_reader_properties->set_pre_buffer(true);
options->fragment_scan_options = fragment_scan_options;
options->use_threads = true;
ScannerBuilder builder(ArithmeticDatasetFixture::schema(), fragment,
options);
ASSERT_OK(builder.UseThreads(true));
ASSERT_OK(builder.BatchSize(128));
ASSERT_OK_AND_ASSIGN(scanner, builder.Finish());
}
ASSERT_OK_AND_ASSIGN(auto batch, scanner->Head(10000));
ASSERT_OK_AND_ASSIGN(batch, scanner->Head(80000 * 10));
// ASSERT_OK_AND_ASSIGN(batch, scanner->Head(8000 * 10));
// Random ReadAsync calls
for (int yy = 0; yy < 100; yy++) {
[[maybe_unused]] auto ff =
buffer_reader->ReadAsync(::arrow::io::IOContext(), 0, 1001);
}
scanner = nullptr;
}
}
```
@bkietz When we have too many Future, the done might notify too many "done",
which might cause stack overflow...
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