[HBASE-10662] RegionScanner is never closed if the region has been moved-out or re-opened when performing scan request

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.98.1, 0.99.0
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: Honghua Feng
• Reporter: Honghua Feng
• Created: 04/Mar/14 09:01
• Updated: 21/Feb/15 23:29
• Resolved: 06/Mar/14 01:43

Description

During regionserver processes scan request from client, it fails the request by throwing a wrapped NotServingRegionException to client if it finds the region related to the passed-in scanner-id has been re-opened, and it also removes the RegionScannerHolder from the scanners. In fact under this case, the old and invalid RegionScanner related to the passed-in scanner-id should be closed and the related lease should be cancelled at the mean time as well.

Currently region's related scanners aren't closed when closing the region, a region scanner is closed only when requested explicitly by client, or by expiration of the related lease, in this sense the close of region scanners is quite passive and lag.

When regionserver processes scan request from client and can't find online region corresponding to the passed-in scanner-id (due to being moved out) or find the region has been re-opened, it throws NotServingRegionException and removes the corresponding RegionScannerHolder from scanners without closing the related region scanner (nor cancelling the related lease), but when the lease expires, the related region scanner still doesn't be closed since it doesn't present in scanners now.