gitedmond opened a new pull request, #51603: URL: https://github.com/apache/arrow/pull/51603
### Rationale for this change Fixes #51547. The IPC dataset scan opens a reader asynchronously, then synchronously reopens it to apply projected fields. The synchronous reopen can wait for footer IO while a generator lock is held, creating the blocking cycle described in the issue. ### What changes are included in this PR? - Use the existing `OpenReaderAsync` path for the projected reader reopen. - Add a controlled C++ regression test that gates the second reader’s footer read and checks that scan setup and a CPU worker can make progress before that read completes. ### Are these changes tested? - Before the fix, the new regression failed at the expected blocking assertion in 10/10 runs. - After the fix, the identical regression passed in 100/100 runs. - The other 34 tests in `arrow-dataset-file-ipc-test` passed. - `git diff --check` and formatting of changed lines passed. The reporter’s intermittent R workload was not reproduced here; this test isolates the blocking reader reopen that their stacks identified. ### Are there any user-facing changes? IPC dataset scans no longer block during the projected reader reopen. There is no public API change. ### Was AI used for this PR? **PR code and description written by:** - [ ] Human - [x] AI **Reviewed before submission by:** - [ ] Human - [x] AI - [ ] Not reviewed AI assistance implemented the C++ change and regression test, inspected the code path, and ran the before/after tests. This draft is available for human review. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
