public virtual void TestNodeCount()
{
// start a mini dfs cluster of 2 nodes
Configuration conf = new HdfsConfiguration();
MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).NumDataNodes(ReplicationFactor
).Build();
try
{
FSNamesystem namesystem = cluster.GetNamesystem();
BlockManager bm = namesystem.GetBlockManager();
HeartbeatManager hm = bm.GetDatanodeManager().GetHeartbeatManager();
FileSystem fs = cluster.GetFileSystem();
// populate the cluster with a one block file
Path FilePath = new Path("/testfile");
DFSTestUtil.CreateFile(fs, FilePath, 1L, ReplicationFactor, 1L);
DFSTestUtil.WaitReplication(fs, FilePath, ReplicationFactor);
ExtendedBlock block = DFSTestUtil.GetFirstBlock(fs, FilePath);
// keep a copy of all datanode descriptor
DatanodeDescriptor[] datanodes = hm.GetDatanodes();
// start two new nodes
cluster.StartDataNodes(conf, 2, true, null, null);
cluster.WaitActive();
// bring down first datanode
DatanodeDescriptor datanode = datanodes[0];
MiniDFSCluster.DataNodeProperties dnprop = cluster.StopDataNode(datanode.GetXferAddr
());
// make sure that NN detects that the datanode is down
BlockManagerTestUtil.NoticeDeadDatanode(cluster.GetNameNode(), datanode.GetXferAddr
());
// the block will be replicated
DFSTestUtil.WaitReplication(fs, FilePath, ReplicationFactor);
// restart the first datanode
cluster.RestartDataNode(dnprop);
cluster.WaitActive();
// check if excessive replica is detected (transient)
InitializeTimeout(Timeout);
while (CountNodes(block.GetLocalBlock(), namesystem).ExcessReplicas() == 0)
{
CheckTimeout("excess replicas not detected");
}
// find out a non-excess node
DatanodeDescriptor nonExcessDN = null;
foreach (DatanodeStorageInfo storage in bm.blocksMap.GetStorages(block.GetLocalBlock
()))
{
DatanodeDescriptor dn = storage.GetDatanodeDescriptor();
ICollection <Block> blocks = bm.excessReplicateMap[dn.GetDatanodeUuid()];
if (blocks == null || !blocks.Contains(block.GetLocalBlock()))
{
nonExcessDN = dn;
break;
}
}
NUnit.Framework.Assert.IsTrue(nonExcessDN != null);
// bring down non excessive datanode
dnprop = cluster.StopDataNode(nonExcessDN.GetXferAddr());
// make sure that NN detects that the datanode is down
BlockManagerTestUtil.NoticeDeadDatanode(cluster.GetNameNode(), nonExcessDN.GetXferAddr
());
// The block should be replicated
InitializeTimeout(Timeout);
while (CountNodes(block.GetLocalBlock(), namesystem).LiveReplicas() != ReplicationFactor
)
{
CheckTimeout("live replica count not correct", 1000);
}
// restart the first datanode
cluster.RestartDataNode(dnprop);
cluster.WaitActive();
// check if excessive replica is detected (transient)
InitializeTimeout(Timeout);
while (CountNodes(block.GetLocalBlock(), namesystem).ExcessReplicas() != 2)
{
CheckTimeout("excess replica count not equal to 2");
}
}
finally
{
cluster.Shutdown();
}
}