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HDFS-11609. Some blocks can be permanently lost if nodes are decommissioned while dead. Contributed by Kihwal Lee.

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This commit is contained in:
Kihwal Lee 2017-05-01 14:28:27 -05:00
parent 993ab15b39
commit d1e6b6db7c
3 changed files with 130 additions and 8 deletions
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21
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java
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@ -1766,7 +1766,8 @@ List<DatanodeDescriptor> getDatanodeDescriptors(List<String> nodes) {
*
* We prefer nodes that are in DECOMMISSION_INPROGRESS state to other nodes
* since the former do not have write traffic and hence are less busy.
* We do not use already decommissioned nodes as a source.
* We do not use already decommissioned nodes as a source, unless there no
* other choice.
* Otherwise we choose a random node among those that did not reach their
* replication limits. However, if the replication is of the highest priority
* and all nodes have reached their replication limits, we will choose a
@ -1798,6 +1799,7 @@ DatanodeDescriptor chooseSourceDatanode(Block block,
containingNodes.clear();
nodesContainingLiveReplicas.clear();
DatanodeDescriptor srcNode = null;
DatanodeDescriptor decommissionedSrc = null;
int live = 0;
int readonly = 0;
int decommissioned = 0;
@ -1844,9 +1846,16 @@ else if (node.isDecommissionInProgress()) {
// the block must not be scheduled for removal on srcNode
if(excessBlocks != null && excessBlocks.contains(block))
continue;
// never use already decommissioned nodes
if(node.isDecommissioned())
// Save the live decommissioned replica in case we need it. Such replicas
// are normally not used for replication, but if nothing else is
// available, one can be selected as a source.
if (node.isDecommissioned()) {
if (decommissionedSrc == null ||
ThreadLocalRandom.current().nextBoolean()) {
decommissionedSrc = node;
}
continue;
}
// We got this far, current node is a reasonable choice
if (srcNode == null) {
@ -1862,6 +1871,10 @@ else if (node.isDecommissionInProgress()) {
if(numReplicas != null)
numReplicas.set(live, readonly, decommissioned, decommissioning, corrupt,
excess, 0);
// Pick a live decommissioned replica, if nothing else is available.
if (live == 0 && srcNode == null && decommissionedSrc != null) {
return decommissionedSrc;
}
return srcNode;
}
@ -2677,7 +2690,7 @@ private Block addStoredBlock(final BlockInfo block,
int curReplicaDelta;
if (result == AddBlockResult.ADDED) {
curReplicaDelta = 1;
curReplicaDelta = (node.isDecommissioned()) ? 0 : 1;
if (logEveryBlock) {
blockLog.debug("BLOCK* addStoredBlock: {} is added to {} (size={})",
node, storedBlock, storedBlock.getNumBytes());

6
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/UnderReplicatedBlocks.java
View File

@ -310,9 +310,9 @@ synchronized void update(BlockInfo block, int curReplicas,
" curPri " + curPri +
" oldPri " + oldPri);
}
if(oldPri != curPri) {
remove(block, oldPri);
}
// oldPri is mostly correct, but not always. If not found with oldPri,
// other levels will be searched until the block is found & removed.
remove(block, oldPri);
if(priorityQueues.get(curPri).add(block)) {
NameNode.blockStateChangeLog.debug(
"BLOCK* NameSystem.UnderReplicationBlock.update: {} has only {} " +

111
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDecommissioningStatus.java
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@ -48,6 +48,7 @@
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockManagerTestUtil;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager;
@ -75,6 +76,7 @@ public class TestDecommissioningStatus {
private static FileSystem localFileSys;
private static Configuration conf;
private static Path dir;
private static Logger LOG;
final ArrayList<String> decommissionedNodes = new ArrayList<String>(numDatanodes);
@ -98,7 +100,7 @@ public void setUp() throws Exception {
conf.setInt(DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY, 1);
conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_PENDING_TIMEOUT_SEC_KEY,
4);
conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, 1000);
conf.setInt(DFSConfigKeys.DFS_NAMENODE_REPLICATION_INTERVAL_KEY, 1);
conf.setInt(DFSConfigKeys.DFS_NAMENODE_DECOMMISSION_INTERVAL_KEY, 1);
conf.setLong(DFSConfigKeys.DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY, 1);
@ -111,6 +113,7 @@ public void setUp() throws Exception {
cluster.getNamesystem().getBlockManager().getDatanodeManager()
.setHeartbeatExpireInterval(3000);
Logger.getLogger(DecommissionManager.class).setLevel(Level.DEBUG);
LOG = Logger.getLogger(TestDecommissioningStatus.class);
}
@After
@ -431,4 +434,110 @@ public void testDecommissionDeadDN() throws Exception {
writeConfigFile(localFileSys, excludeFile, null);
dm.refreshNodes(conf);
}
@Test(timeout=120000)
public void testDecommissionLosingData() throws Exception {
ArrayList<String> nodes = new ArrayList<String>(2);
FSNamesystem fsn = cluster.getNamesystem();
BlockManager bm = fsn.getBlockManager();
DatanodeManager dm = bm.getDatanodeManager();
Path file1 = new Path("decommissionLosingData.dat");
writeFile(fileSys, file1, (short)numDatanodes);
Thread.sleep(1000);
// Shutdown dn1
LOG.info("Shutdown dn1");
DatanodeID dnID = cluster.getDataNodes().get(1).getDatanodeId();
String dnName = dnID.getXferAddr();
DatanodeDescriptor dnDescriptor1 = dm.getDatanode(dnID);
nodes.add(dnName);
DataNodeProperties stoppedDN1 = cluster.stopDataNode(1);
DFSTestUtil.waitForDatanodeState(cluster, dnID.getDatanodeUuid(),
false, 30000);
// Shutdown dn0
LOG.info("Shutdown dn0");
dnID = cluster.getDataNodes().get(0).getDatanodeId();
dnName = dnID.getXferAddr();
DatanodeDescriptor dnDescriptor0 = dm.getDatanode(dnID);
nodes.add(dnName);
DataNodeProperties stoppedDN0 = cluster.stopDataNode(0);
DFSTestUtil.waitForDatanodeState(cluster, dnID.getDatanodeUuid(),
false, 30000);
// Decommission the nodes.
LOG.info("Decommissioning nodes");
writeConfigFile(localFileSys, excludeFile, nodes);
dm.refreshNodes(conf);
BlockManagerTestUtil.recheckDecommissionState(dm);
assertTrue(dnDescriptor0.isDecommissioned());
assertTrue(dnDescriptor1.isDecommissioned());
// All nodes are dead and decommed. Blocks should be missing.
long missingBlocks = bm.getMissingBlocksCount();
long underreplicated = bm.getUnderReplicatedBlocksCount();
assertTrue(missingBlocks > 0);
assertTrue(underreplicated > 0);
// Bring back dn0
LOG.info("Bring back dn0");
cluster.restartDataNode(stoppedDN0, true);
do {
dnID = cluster.getDataNodes().get(0).getDatanodeId();
} while (dnID == null);
dnDescriptor0 = dm.getDatanode(dnID);
// Wait until it sends a block report.
while (dnDescriptor0.numBlocks() == 0) {
Thread.sleep(100);
}
// Bring back dn1
LOG.info("Bring back dn1");
cluster.restartDataNode(stoppedDN1, true);
do {
dnID = cluster.getDataNodes().get(1).getDatanodeId();
} while (dnID == null);
dnDescriptor1 = dm.getDatanode(dnID);
// Wait until it sends a block report.
while (dnDescriptor1.numBlocks() == 0) {
Thread.sleep(100);
}
// Blocks should be still be under-replicated
Thread.sleep(2000); // Let replication monitor run
assertEquals(underreplicated, bm.getUnderReplicatedBlocksCount());
// Start up a node.
LOG.info("Starting two more nodes");
cluster.startDataNodes(conf, 2, true, null, null);
cluster.waitActive();
// Replication should fix it.
int count = 0;
while((bm.getUnderReplicatedBlocksCount() > 0 ||
bm.getPendingReplicationBlocksCount() > 0) &&
count++ < 10) {
Thread.sleep(1000);
}
assertEquals(0, bm.getUnderReplicatedBlocksCount());
assertEquals(0, bm.getPendingReplicationBlocksCount());
assertEquals(0, bm.getMissingBlocksCount());
// Shutdown the extra nodes.
dnID = cluster.getDataNodes().get(3).getDatanodeId();
cluster.stopDataNode(3);
DFSTestUtil.waitForDatanodeState(cluster, dnID.getDatanodeUuid(),
false, 30000);
dnID = cluster.getDataNodes().get(2).getDatanodeId();
cluster.stopDataNode(2);
DFSTestUtil.waitForDatanodeState(cluster, dnID.getDatanodeUuid(),
false, 30000);
// Call refreshNodes on FSNamesystem with empty exclude file to remove the
// datanode from decommissioning list and make it available again.
writeConfigFile(localFileSys, excludeFile, null);
dm.refreshNodes(conf);
fileSys.delete(file1, false);
}
}