[HBASE-9785] Fix heap size reporting in HRegion

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.96.0
• Fix Version/s: 0.98.0, 0.96.1
• Hadoop Flags: Reviewed
• Assignee: Himanshu Vashishtha
• Reporter: Himanshu Vashishtha
• Created: 16/Oct/13 23:08
• Updated: 16/Dec/13 18:46
• Resolved: 23/Oct/13 20:50

Description

The size reported by Fixed_Overhead variable in HRegion misses out on a boolean variable. TestHeapSize doesn't report it because of the alignment we do to make it multiple of 8.

The equation for HRegion heap usage from Fixed_Overhead is:
Fixed_Overhead = align(100 + 42*ref + 1 arr) = align(284) = 288 on a 32 bit vm
(On a 32 bit vm, 1 ref = 4bytes, 1 arr = 16 bytes)

The equation formed using reflection (in Classsize) is:
Expected_Overehead = align(101 + 42*ref + 1arr) = align(285) = 288.
So, the testHeapSize doesn't fail currently.

But if I add a reference (did in last patch in 8741), it starts failing because, now the equations are:
Fixed_Overhead = align(100 + 43*ref + 1 arr) = align(288) = 288
Expected_Overhead = align(101 + 43*ref + 1 arr) = align(289) = 296.