[HBASE-17245] Replace HTableDescriptor#htd.getColumnFamilies().length with a low-cost implementation

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.0.0
• Hadoop Flags: Reviewed
• Assignee: Hua Xiang
• Reporter: Hua Xiang
• Created: 02/Dec/16 23:07
• Updated: 05/Dec/16 09:35
• Resolved: 05/Dec/16 07:59

Description

Found quite a few places doing something like

    if (htd.getColumnFamilies().length == 0) {

HTableDescriptor#htd.getColumnFamilies() does a few memory allocations. The purpose is to get the family number, it can be replaced with

+  public int getColumnFamilyCount() {
 +    return families.size();
 +  }

in HTableDescriptor which does not need these memory allocations.