[HBASE-5978] Scanner next() calls should return after a configurable time threshold regardless of number of accumulated rows

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 0.90.7, 0.92.1
• Component/s: Client, regionserver
• Assignee: Unassigned
• Reporter: Todd Lipcon
• Created: 09/May/12 22:14
• Updated: 13/Jun/22 16:36
• Resolved: 08/Apr/15 19:26

Description

Currently if you pass a very restrictive filter to a scanner, along with a high caching value, you will end up causing RPC timeouts, lease exceptions, etc. Although this is a poor configuration and easy to work around by lowering caching, HBase should be resilient to a badly chosen caching value. As such, the scanner next() call should record the elapsed time, and after some number of seconds have passed, return any accumulated rows regardless of the caching value. This prevents the calls from starving out other threads or region operations.