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From keith-turner <...@git.apache.org>
Subject [GitHub] accumulo pull request #220: ACCUMULO-4591 replication latency metrics added
Date Thu, 23 Feb 2017 17:50:39 GMT
Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/220#discussion_r102774271
  
    --- Diff: server/master/src/main/java/org/apache/accumulo/master/replication/RemoveCompleteReplicationRecords.java
---
    @@ -216,4 +220,13 @@ protected long removeRowIfNecessary(BatchWriter bw, SortedMap<Key,Value>
columns
     
         return recordsRemoved;
       }
    +
    +  /*
    +   * Metrics calls snapshot. Largest time stamp will be found for each snapshot then
reset.
    +   */
    +  private void collectLatency(Long createdTime) {
    +    long latency = System.currentTimeMillis() - createdTime;
    --- End diff --
    
    I looked into this a bit more to see if using nanoTime would be reasonable across processes.
 The following is from the nanoTime javaodc
    
    ```
    Returns the current value of the running Java Virtual Machine's high-resolution time source,
in nanoseconds. This method can only be used to measure elapsed time and is not related to
any other notion of system or wall-clock time.
    ```
    
    Given this documentation, if the times are persisted and used across multiple processes
then I think using `nanoTime()` would be inappropriate. 


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