ziglerari opened a new issue, #43447: URL: https://github.com/apache/arrow/issues/43447
### Describe the bug, including details regarding any error messages, version, and platform. A [gRPC issue](https://github.com/grpc/grpc/pull/37255) has been identified where transmitting buffers of zero length leads to a persistent hang on MacOS/iOS platforms. Such zero-length buffers may arise, for example, in the context of using the Array structure alongside a validity bitmap, as outlined in the [Arrow Spec](https://arrow.apache.org/docs/format/Columnar.html#validity-bitmaps). Essentially, when every element within an Array is valid (i.e., not null), it's possible to represent this state with a null validity bitmap, indicating that all elements are valid. This scenario is realized through the use of a null buffer, as demonstrated here: https://github.com/apache/arrow/blob/187197c369058f7d1377c1b161c469a9e4542caf/cpp/src/arrow/ipc/writer.cc#L165-L179 The relevant sections of code from both transport mechanisms are provided below for reference: https://github.com/apache/arrow/blob/187197c369058f7d1377c1b161c469a9e4542caf/cpp/src/arrow/flight/transport/grpc/serialization_internal.cc#L283-L287 https://github.com/apache/arrow/blob/187197c369058f7d1377c1b161c469a9e4542caf/cpp/src/arrow/flight/transport/ucx/ucx_internal.cc#L590-L591 Upon examining the UCX transport's approach, it's evident that a precaution is taken to avoid sending zero-length buffers. This strategy appears prudent, as it eliminates the need to forward non-transmittable buffers to the transport layer, potentially offering a solution to the issue observed with gRPC. ### Component(s) C++, FlightRPC -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@arrow.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
