[HDFS-9748] When addExpectedReplicasToPending is called twice, pendingReplications should avoid duplication

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.8.0
• Fix Version/s: 2.8.0, 3.0.0-alpha1
• Hadoop Flags: Reviewed
• Assignee: Walter Su
• Reporter: Walter Su
• Created: 03/Feb/16 12:53
• Updated: 30/Aug/16 01:20
• Resolved: 03/Feb/16 21:35

Description

1. When completeFile() is called, addExpectedReplicasToPending() will be called (HDFS-8999).

2. When first replica is reported, addExpectedReplicasToPending() will be called the second time.

//BlockManager.addStoredBlock(..)
    if(storedBlock.getBlockUCState() == BlockUCState.COMMITTED &&
        hasMinStorage(storedBlock, numLiveReplicas)) {
      addExpectedReplicasToPending(storedBlock, bc);
      completeBlock(storedBlock, false);
    } else if (storedBlock.isComplete() && result == AddBlockResult.ADDED) {

But,

//PendingReplicationBlocks.java
    void incrementReplicas(DatanodeDescriptor... newTargets) {
      if (newTargets != null) {
        Collections.addAll(targets, newTargets);
      }
    }

targets is ArrayList, the above code simply add all newTargets to targets.