[ARROW-11590] [C++] Move CSV background generator to IO thread pool

• Type: Task
• 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/27460
• Assignee: Weston Pace
• Reporter: Weston Pace
• Created: 10/Feb/21 19:11
• Updated: 11/Jan/23 08:20
• Resolved: 15/Mar/21 13:48

Description

The current readahead accomplishes its task by using an async reentrant readahead.  We get away with this today because the background generator is async reentrant because it runs on a thread pool of size 1 and so the underlying thread pool can only iterate the underlying iterator synchronously.

However, in order to move to the I/O thread pool we need a readahead operator that is does not pull reentrantly.

This can be done either by submitting the next task as soon as the previous one is done or by creating a "serial concurrency" executor that wraps an underlying executor.  Both approaches will need a queue so this can be done after ARROW-11588

Issue Links

• Dependent: ARROW-11588 [C++] Add traceable general purpose queue(s)
• links to: GitHub Pull Request #9533