[IMPALA-6121] Remove RequestContext cache in DiskIoMgr

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.11.0
• Fix Version/s: Impala 2.11.0
• Component/s: Backend
• Target Version: Product Backlog
• Epic Color: ghx-label-9
• Assignee: Tim Armstrong
• Reporter: Tim Armstrong
• Created: 27/Oct/17 22:16
• Updated: 15/Nov/17 22:06
• Resolved: 15/Nov/17 22:06

Description

I'm planning to do some work on the I/O manager buffer management. I think the lifecycle of request contexts is more complex than necessary because of the recycling. That recycling is unlikely to save CPU cycles or improve scalability relative to TCMalloc since the cache is behind a single global lock.