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HDFS-7742. Favoring decommissioning node for replication can cause a block to stay 

underreplicated for long periods. Contributed by Nathan Roberts.
(cherry picked from commit 04ee18ed48)

(cherry picked from commit c4cedfc1d6)
(cherry picked from commit c6b68a82adea8de488b255594d35db8e01f5fc8f)
This commit is contained in:
Kihwal Lee 2015-03-30 10:11:25 -05:00 committed by Vinod Kumar Vavilapalli
parent 0b1e66f01d
commit bc8728cd27
3 changed files with 50 additions and 5 deletions
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3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
View File

@ -109,6 +109,9 @@ Release 2.6.1 - UNRELEASED
HDFS-7960. The full block report should prune zombie storages even if
they're not empty. (cmccabe and Eddy Xu via wang)
HDFS-7742. Favoring decommissioning node for replication can cause a block
to stay underreplicated for long periods (Nathan Roberts via kihwal)
Release 2.6.0 - 2014-11-18
INCOMPATIBLE CHANGES

10
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
View File

@ -1652,7 +1652,8 @@ public class BlockManager {
// If so, do not select the node as src node
if ((nodesCorrupt != null) && nodesCorrupt.contains(node))
continue;
if(priority != UnderReplicatedBlocks.QUEUE_HIGHEST_PRIORITY
if(priority != UnderReplicatedBlocks.QUEUE_HIGHEST_PRIORITY
&& !node.isDecommissionInProgress()
&& node.getNumberOfBlocksToBeReplicated() >= maxReplicationStreams)
{
continue; // already reached replication limit
@ -1667,13 +1668,12 @@ public class BlockManager {
// never use already decommissioned nodes
if(node.isDecommissioned())
continue;
// we prefer nodes that are in DECOMMISSION_INPROGRESS state
if(node.isDecommissionInProgress() || srcNode == null) {
// We got this far, current node is a reasonable choice
if (srcNode == null) {
srcNode = node;
continue;
}
if(srcNode.isDecommissionInProgress())
continue;
// switch to a different node randomly
// this to prevent from deterministically selecting the same node even
// if the node failed to replicate the block on previous iterations

42
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java
View File

@ -535,6 +535,48 @@ public class TestBlockManager {
UnderReplicatedBlocks.QUEUE_HIGHEST_PRIORITY));
}
@Test
public void testFavorDecomUntilHardLimit() throws Exception {
bm.maxReplicationStreams = 0;
bm.replicationStreamsHardLimit = 1;
long blockId = 42; // arbitrary
Block aBlock = new Block(blockId, 0, 0);
List<DatanodeDescriptor> origNodes = getNodes(0, 1);
// Add the block to the first node.
addBlockOnNodes(blockId,origNodes.subList(0,1));
origNodes.get(0).startDecommission();
List<DatanodeDescriptor> cntNodes = new LinkedList<DatanodeDescriptor>();
List<DatanodeStorageInfo> liveNodes = new LinkedList<DatanodeStorageInfo>();
assertNotNull("Chooses decommissioning source node for a normal replication"
+ " if all available source nodes have reached their replication"
+ " limits below the hard limit.",
bm.chooseSourceDatanode(
aBlock,
cntNodes,
liveNodes,
new NumberReplicas(),
UnderReplicatedBlocks.QUEUE_UNDER_REPLICATED));
// Increase the replication count to test replication count > hard limit
DatanodeStorageInfo targets[] = { origNodes.get(1).getStorageInfos()[0] };
origNodes.get(0).addBlockToBeReplicated(aBlock, targets);
assertNull("Does not choose a source decommissioning node for a normal"
+ " replication when all available nodes exceed the hard limit.",
bm.chooseSourceDatanode(
aBlock,
cntNodes,
liveNodes,
new NumberReplicas(),
UnderReplicatedBlocks.QUEUE_UNDER_REPLICATED));
}
@Test
public void testSafeModeIBR() throws Exception {
DatanodeDescriptor node = spy(nodes.get(0));