[HBASE-16300] LruBlockCache.CACHE_FIXED_OVERHEAD should calculate LruBlockCache size correctly

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.0, 0.98.21, 1.2.3, 2.0.0
• Assignee: Yu Sun
• Reporter: Yu Sun
• Created: 28/Jul/16 18:51
• Updated: 29/Jul/16 18:02
• Resolved: 29/Jul/16 06:36

Description

in current master LruBlockCache, CACHE_FIXED_OVERHEAD is calculated as this:

  public final static long CACHE_FIXED_OVERHEAD = ClassSize.align(
      (3 * Bytes.SIZEOF_LONG) + (10 * ClassSize.REFERENCE) +
      (5 * Bytes.SIZEOF_FLOAT) + (2 * Bytes.SIZEOF_BOOLEAN)
      + ClassSize.OBJECT);

after some investigation. I think there are some wrong here, class LruBlockCache, except static varible(which is belongs to class), there are 4 long varibles(maxBlockSize,maxSize,blockSize and overhead), 9 reference varibles and 2 boolean varibles, so the above code will not calculate LruBlockCache instance size correctly.

current related ut not failed mostly due to the result is 8 bytes aligned.

Issue Links

• Blocked: HBASE-16287 LruBlockCache size should not exceed acceptableSize too many
• is broken by: HBASE-14793 Allow limiting size of block into L1 block cache.