[HBASE-6217] reduce overhead of maintaing get/next size metric

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Abandoned
• Labels: patch
• Assignee: Unassigned
• Reporter: Kannan Muthukkaruppan
• Created: 15/Jun/12 17:28
• Updated: 13/Jun/22 16:51
• Resolved: 13/Jun/22 16:51

Description

[Forked off this specific issue as a separate JIRA from HBASE-6066].

Reduce overhead of "size metric" maintained in StoreScanner.next().

if (metric != null) {
     HRegion.incrNumericMetric(this.metricNamePrefix + metric,
                               copyKv.getLength());
  }
  results.add(copyKv);

A single call to next() might fetch a lot of KVs. We can first add up the size of those KVs in a local variable and then in a finally clause increment the metric one shot, rather than updating AtomicLongs for each KV.