[HBASE-10117] Avoid synchronization in HRegionScannerImpl.isFilterDone

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.94.15, 0.96.2, 0.98.1, 0.99.0
• Component/s: Performance
• Hadoop Flags: Reviewed
• Assignee: Lars Hofhansl
• Reporter: Lars Hofhansl
• Created: 10/Dec/13 05:08
• Updated: 30/Dec/13 04:11
• Resolved: 10/Dec/13 18:28

Description

A while ago I introduced HRegoinScannerImpl.nextRaw() to allow coprocessors and scanners with caching > 1 to avoid repeated synchronization during scanning (which puts up memory fences, which in turn slows things down on multi core machines).

Looking at the code again I see that isFilterDone() is called from nextRaw() and isFilterDone() is synchronized.
The caller of nextRaw is required to ensure single threaded access to nextRaw() anyway, we can call an unsynchronized internal version of isFilterDone().