[ https://issues.apache.org/jira/browse/TEPHRA-266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16458846#comment-16458846 ] 

ASF GitHub Bot commented on TEPHRA-266:
---------------------------------------

Github user poornachandra commented on a diff in the pull request:

    https://github.com/apache/incubator-tephra/pull/74#discussion_r185070466
  
    --- Diff: tephra-core/src/main/java/org/apache/tephra/coprocessor/TransactionStateCache.java ---
    @@ -184,4 +185,14 @@ private void refreshState() throws IOException {
       public TransactionVisibilityState getLatestState() {
         return latestState;
       }
    +
    +  protected void setId(@Nullable String id) {
    +    if (id != null) {
    +      this.logPrefix = "[" + id + "] ";
    +    }
    +  }
    +
    +  private String prefixLog(String message) {
    --- End diff --
    
    HBase co-processor uses Apache commons-logging. The `{}` notation is not available in the commons-logging APIs.
    
    I couldn't figure out a way to not create a string unless absolutely necessary. The only debug log in that file has `LOG.isDebugEnabled()` guard. However, I know this is not an ideal solution.


> Identify log messages when multiple instances of Tephra run on a single HBase cluster
> -------------------------------------------------------------------------------------
>
>                 Key: TEPHRA-266
>                 URL: https://issues.apache.org/jira/browse/TEPHRA-266
>             Project: Tephra
>          Issue Type: Improvement
>         Environment: 
>            Reporter: Poorna Chandra
>            Assignee: Poorna Chandra
>            Priority: Major
>             Fix For: 0.14.0-incubating
>
>
> When multiple instances of Tehpra are run in a single HBase cluster, the log messages from the co-processors of all instances (which are identical except for the timestamp) go into a single region server log file. It becomes very difficult to figure out issues of an instance due to this.
> it would be good if instance id is logged along with the co-processor log messages so that we can identity which messages belong to which instance of Tephra.



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