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From keith-turner <...@git.apache.org>
Subject [GitHub] accumulo pull request #270: ACCUMULO-4657 Reduce excessive logging / logging...
Date Tue, 20 Jun 2017 16:18:02 GMT
Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/270#discussion_r123024515
  
    --- Diff: server/base/src/main/java/org/apache/accumulo/server/util/MetadataTableUtil.java
---
    @@ -894,12 +895,19 @@ public static void removeBulkLoadEntries(Connector conn, String
tableId, long ti
             BatchWriter bw = conn.createBatchWriter(MetadataTable.NAME, new BatchWriterConfig()))
{
           mscanner.setRange(new KeyExtent(tableId, null, null).toMetadataRange());
           mscanner.fetchColumnFamily(TabletsSection.BulkFileColumnFamily.NAME);
    +      boolean shouldTrace = log.isTraceEnabled();
    +      byte[] tidAsBytes = Long.toString(tid).getBytes(UTF_8);
           for (Entry<Key,Value> entry : mscanner) {
    -        log.debug("Looking at entry " + entry + " with tid " + tid);
    -        if (Long.parseLong(entry.getValue().toString()) == tid) {
    -          log.debug("deleting entry " + entry);
    -          Mutation m = new Mutation(entry.getKey().getRow());
    -          m.putDelete(entry.getKey().getColumnFamily(), entry.getKey().getColumnQualifier());
    +        if (shouldTrace) {
    +          log.trace("Looking at entry " + entry + " with tid " + tid);
    --- End diff --
    
    This is not related to this PR, but its something I learned about slf4j vs log4j.  This
conversation reminded me of it and I thought it was worth sharing.
    
    Varargs methods can be expensive in a tight loop, because it allocates an array and copies
to it.  Slf4j avoids this for one and two arguments by providing specialized methods.  However
3 or more args will use varargs.  
    
    I learned from @EdColeman that log4j V2  provides specialized methods for up to 10 arguments
to avoid varargs. For example this is the [debug method that takes 10 args](https://logging.apache.org/log4j/2.x/log4j-api/apidocs/org/apache/logging/log4j/Logger.html#debug-org.apache.logging.log4j.Marker-java.lang.String-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-java.lang.Object-)
    
    Wish slf4j had this.


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