[ARROW-13417] [C++] The merged generator can sometimes pull from source sync-reentrant

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/29085
• Assignee: Weston Pace
• Reporter: Weston Pace
• Created: 20/Jul/21 21:09
• Updated: 11/Jan/23 08:32
• Resolved: 20/Jul/21 23:50

Description

Async generators make no promises about whether or not they are synchronously reentrant and they should never be pulled in a synchronously reentrant fashion.  The merged generator is breaking this rule.

Issue Links

• relates to: ARROW-13198 [C++][Dataset] Async scanner occasionally segfaulting in CI
• links to: GitHub Pull Request #10758