[jira] [Created] (HDFS-14108) BlockManager Data Structures

["BELUGA BEHR (JIRA)" <ji...@apache.org>]

BELUGA BEHR created HDFS-14108:
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             Summary: BlockManager Data Structures
                 Key: HDFS-14108
                 URL: https://issues.apache.org/jira/browse/HDFS-14108
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: hdfs
    Affects Versions: 3.2.0
            Reporter: BELUGA BEHR
            Assignee: BELUGA BEHR
         Attachments: HDFS-14108.1.patch

# Prefer {{ArrayList}} to {{LinkedList}} when simply adding/iterating
# Prefer {{HashSet}} to {{TreeSet}} when no ordering is required
# Other performance improvements
# Check style fixes

https://stackoverflow.com/questions/322715/when-to-use-linkedlist-over-arraylist-in-java

{code:java}
    final Set<Node> excludedNodes = new HashSet<>();
    for(BlockReconstructionWork rw : reconWork){
      // Do no bother wasting time clearing out the collection, let GC do that work later
      excludedNodes.clear();
      // use {{addAll}} here
      for (DatanodeDescriptor dn : rw.getContainingNodes()) {
        excludedNodes.add(dn);
      }
{code}



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