[ARROW-11942] [C++] If tasks are submitted quickly the thread pool may fail to spin up new threads

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/27778
• Assignee: Weston Pace
• Reporter: Weston Pace
• Created: 12/Mar/21 02:27
• Updated: 11/Jan/23 08:23
• Resolved: 15/Mar/21 12:28

Description

Probably only really affects unit tests.  Consider an idle thread pool with 1 thread (ready_count_ == 1).  If `Spawn` is called very quickly it may look like `ready_count_` is still greater than 0 (because `ready_count_` doesn't necessarily decrement by the time `Spawn` returns) and so it will not spin up new threads.

Issue Links

• links to: GitHub Pull Request #9684