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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hdfs;
import org.apache.hadoop.classification.VisibleForTesting;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.DatanodeLocalInfo;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.util.Daemon;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.Deque;
import java.util.LinkedList;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_CONNECTION_TIMEOUT_MS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_CONNECTION_TIMEOUT_MS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_INTERVAL_MS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_INTERVAL_MS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_THREADS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_THREADS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_INTERVAL_MS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_INTERVAL_MS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_THREADS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_THREADS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_RPC_THREADS_DEFAULT;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_RPC_THREADS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_SOCKET_TIMEOUT_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_IDLE_SLEEP_MS_KEY;
import static org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.DFS_CLIENT_DEAD_NODE_DETECTION_IDLE_SLEEP_MS_DEFAULT;
/**
* Detect the dead nodes in advance, and share this information among all the
* DFSInputStreams in the same client.
*/
public class DeadNodeDetector extends Daemon {
public static final Logger LOG =
LoggerFactory.getLogger(DeadNodeDetector.class);
/**
* Waiting time when DeadNodeDetector happens error.
*/
private static final long ERROR_SLEEP_MS = 5000;
/**
* Waiting time when DeadNodeDetector's state is idle.
*/
private final long idleSleepMs;
/**
* Client context name.
*/
private String name;
private Configuration conf;
/**
* Dead nodes shared by all the DFSInputStreams of the client.
*/
private final Map deadNodes;
/**
* Record suspect and dead nodes by one DFSInputStream. When node is not used
* by one DFSInputStream, remove it from suspectAndDeadNodes#DFSInputStream.
* If DFSInputStream does not include any node, remove DFSInputStream from
* suspectAndDeadNodes.
*/
private final Map>
suspectAndDeadNodes;
/**
* Datanodes that is being probed.
*/
private Map probeInProg =
new ConcurrentHashMap();
/**
* Interval time in milliseconds for probing dead node behavior.
*/
private long deadNodeDetectInterval = 0;
/**
* Interval time in milliseconds for probing suspect node behavior.
*/
private long suspectNodeDetectInterval = 0;
/**
* Connection timeout for probing dead node in milliseconds.
*/
private long probeConnectionTimeoutMs;
/**
* The dead node probe queue.
*/
private UniqueQueue deadNodesProbeQueue;
/**
* The suspect node probe queue.
*/
private UniqueQueue suspectNodesProbeQueue;
/**
* The thread pool of probing dead node.
*/
private ExecutorService probeDeadNodesThreadPool;
/**
* The thread pool of probing suspect node.
*/
private ExecutorService probeSuspectNodesThreadPool;
/**
* The scheduler thread of probing dead node.
*/
private Thread probeDeadNodesSchedulerThr;
/**
* The scheduler thread of probing suspect node.
*/
private Thread probeSuspectNodesSchedulerThr;
/**
* The thread pool of probing datanodes' rpc request. Sometimes the data node
* can hang and not respond to the client in a short time. And these node will
* filled with probe thread pool and block other normal node probing.
*/
private ExecutorService rpcThreadPool;
private int socketTimeout;
/**
* The type of probe.
*/
private enum ProbeType {
CHECK_DEAD, CHECK_SUSPECT
}
/**
* The state of DeadNodeDetector.
*/
private enum State {
INIT, CHECK_DEAD, IDLE, ERROR
}
/**
* The thread safe unique queue.
*/
static class UniqueQueue {
private Deque queue = new LinkedList<>();
private Set set = new HashSet<>();
synchronized boolean offer(T dn) {
if (set.add(dn)) {
queue.addLast(dn);
return true;
}
return false;
}
synchronized T poll() {
T dn = queue.pollFirst();
set.remove(dn);
return dn;
}
synchronized int size() {
return set.size();
}
}
/**
* Disabled start probe suspect/dead thread for the testing.
*/
private static volatile boolean disabledProbeThreadForTest = false;
private State state;
public DeadNodeDetector(String name, Configuration conf) {
this.conf = new Configuration(conf);
this.deadNodes = new ConcurrentHashMap();
this.suspectAndDeadNodes =
new ConcurrentHashMap>();
this.name = name;
deadNodeDetectInterval = conf.getLong(
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_INTERVAL_MS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_INTERVAL_MS_DEFAULT);
suspectNodeDetectInterval = conf.getLong(
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_INTERVAL_MS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_INTERVAL_MS_DEFAULT);
socketTimeout =
conf.getInt(DFS_CLIENT_SOCKET_TIMEOUT_KEY, HdfsConstants.READ_TIMEOUT);
probeConnectionTimeoutMs = conf.getLong(
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_CONNECTION_TIMEOUT_MS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_CONNECTION_TIMEOUT_MS_DEFAULT);
this.deadNodesProbeQueue = new UniqueQueue<>();
this.suspectNodesProbeQueue = new UniqueQueue<>();
idleSleepMs = conf.getLong(DFS_CLIENT_DEAD_NODE_DETECTION_IDLE_SLEEP_MS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_IDLE_SLEEP_MS_DEFAULT);
int deadNodeDetectDeadThreads =
conf.getInt(DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_THREADS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_DEAD_NODE_THREADS_DEFAULT);
int suspectNodeDetectDeadThreads = conf.getInt(
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_THREADS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_PROBE_SUSPECT_NODE_THREADS_DEFAULT);
int rpcThreads = conf.getInt(DFS_CLIENT_DEAD_NODE_DETECTION_RPC_THREADS_KEY,
DFS_CLIENT_DEAD_NODE_DETECTION_RPC_THREADS_DEFAULT);
probeDeadNodesThreadPool = Executors.newFixedThreadPool(
deadNodeDetectDeadThreads, new Daemon.DaemonFactory());
probeSuspectNodesThreadPool = Executors.newFixedThreadPool(
suspectNodeDetectDeadThreads, new Daemon.DaemonFactory());
rpcThreadPool =
Executors.newFixedThreadPool(rpcThreads, new Daemon.DaemonFactory());
if (!disabledProbeThreadForTest) {
startProbeScheduler();
}
LOG.info("Start dead node detector for DFSClient {}.", this.name);
state = State.INIT;
}
@Override
public void run() {
while (!Thread.currentThread().isInterrupted()) {
clearAndGetDetectedDeadNodes();
LOG.debug("Current detector state {}, the detected nodes: {}.", state,
deadNodes.values());
switch (state) {
case INIT:
init();
break;
case CHECK_DEAD:
checkDeadNodes();
break;
case IDLE:
idle();
break;
case ERROR:
try {
Thread.sleep(ERROR_SLEEP_MS);
} catch (InterruptedException e) {
LOG.debug("Got interrupted while DeadNodeDetector is error.", e);
Thread.currentThread().interrupt();
}
return;
default:
break;
}
}
}
/**
* Shutdown all the threads.
*/
public void shutdown() {
threadShutDown(this);
threadShutDown(probeDeadNodesSchedulerThr);
threadShutDown(probeSuspectNodesSchedulerThr);
probeDeadNodesThreadPool.shutdown();
probeSuspectNodesThreadPool.shutdown();
rpcThreadPool.shutdown();
}
private static void threadShutDown(Thread thread) {
if (thread != null && thread.isAlive()) {
thread.interrupt();
try {
thread.join();
} catch (InterruptedException e) {
}
}
}
@VisibleForTesting
boolean isThreadsShutdown() {
return !this.isAlive() && !probeDeadNodesSchedulerThr.isAlive()
&& !probeSuspectNodesSchedulerThr.isAlive()
&& probeDeadNodesThreadPool.isShutdown()
&& probeSuspectNodesThreadPool.isShutdown()
&& rpcThreadPool.isShutdown();
}
@VisibleForTesting
static void setDisabledProbeThreadForTest(
boolean disabledProbeThreadForTest) {
DeadNodeDetector.disabledProbeThreadForTest = disabledProbeThreadForTest;
}
/**
* Start probe dead node and suspect node thread.
*/
@VisibleForTesting
void startProbeScheduler() {
probeDeadNodesSchedulerThr =
new Thread(new ProbeScheduler(this, ProbeType.CHECK_DEAD));
probeDeadNodesSchedulerThr.setDaemon(true);
probeDeadNodesSchedulerThr.start();
probeSuspectNodesSchedulerThr =
new Thread(new ProbeScheduler(this, ProbeType.CHECK_SUSPECT));
probeSuspectNodesSchedulerThr.setDaemon(true);
probeSuspectNodesSchedulerThr.start();
}
/**
* Prode datanode by probe type.
*/
private void scheduleProbe(ProbeType type) {
LOG.debug("Schedule probe datanode for probe type: {}.", type);
DatanodeInfo datanodeInfo = null;
if (type == ProbeType.CHECK_DEAD) {
while ((datanodeInfo = deadNodesProbeQueue.poll()) != null) {
if (probeInProg.containsKey(datanodeInfo.getDatanodeUuid())) {
LOG.debug("The datanode {} is already contained in probe queue, " +
"skip to add it.", datanodeInfo);
continue;
}
probeInProg.put(datanodeInfo.getDatanodeUuid(), datanodeInfo);
Probe probe = new Probe(this, datanodeInfo, ProbeType.CHECK_DEAD);
probeDeadNodesThreadPool.execute(probe);
}
} else if (type == ProbeType.CHECK_SUSPECT) {
while ((datanodeInfo = suspectNodesProbeQueue.poll()) != null) {
if (probeInProg.containsKey(datanodeInfo.getDatanodeUuid())) {
continue;
}
probeInProg.put(datanodeInfo.getDatanodeUuid(), datanodeInfo);
Probe probe = new Probe(this, datanodeInfo, ProbeType.CHECK_SUSPECT);
probeSuspectNodesThreadPool.execute(probe);
}
}
}
/**
* Request the data node through rpc, and determine the data node status based
* on the returned result.
*/
class Probe implements Runnable {
private DeadNodeDetector deadNodeDetector;
private DatanodeInfo datanodeInfo;
private ProbeType type;
Probe(DeadNodeDetector deadNodeDetector, DatanodeInfo datanodeInfo,
ProbeType type) {
this.deadNodeDetector = deadNodeDetector;
this.datanodeInfo = datanodeInfo;
this.type = type;
}
public DatanodeInfo getDatanodeInfo() {
return datanodeInfo;
}
public ProbeType getType() {
return type;
}
@Override
public void run() {
LOG.debug("Check node: {}, type: {}.", datanodeInfo, type);
try {
final ClientDatanodeProtocol proxy =
DFSUtilClient.createClientDatanodeProtocolProxy(datanodeInfo,
deadNodeDetector.conf, socketTimeout, true);
Future future = rpcThreadPool.submit(new Callable() {
@Override
public DatanodeLocalInfo call() throws Exception {
return proxy.getDatanodeInfo();
}
});
try {
future.get(probeConnectionTimeoutMs, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
LOG.error("Probe failed, datanode: {}, type: {}.", datanodeInfo, type,
e);
deadNodeDetector.probeCallBack(this, false);
return;
} finally {
future.cancel(true);
}
deadNodeDetector.probeCallBack(this, true);
return;
} catch (Exception e) {
LOG.error("Probe failed, datanode: {}, type: {}.", datanodeInfo, type,
e);
deadNodeDetector.probeCallBack(this, false);
}
}
}
/**
* Handle data node, according to probe result. When ProbeType is CHECK_DEAD,
* remove the datanode from DeadNodeDetector#deadNodes if probe success.
*/
private void probeCallBack(Probe probe, boolean success) {
LOG.debug("Probe datanode: {} result: {}, type: {}",
probe.getDatanodeInfo(), success, probe.getType());
probeInProg.remove(probe.getDatanodeInfo().getDatanodeUuid());
if (success) {
if (probe.getType() == ProbeType.CHECK_DEAD) {
LOG.info("Remove the node out from dead node list: {}.",
probe.getDatanodeInfo());
removeDeadNode(probe.getDatanodeInfo());
} else if (probe.getType() == ProbeType.CHECK_SUSPECT) {
LOG.debug("Remove the node out from suspect node list: {}.",
probe.getDatanodeInfo());
removeNodeFromDeadNodeDetector(probe.getDatanodeInfo());
}
} else {
if (probe.getType() == ProbeType.CHECK_SUSPECT) {
LOG.warn("Probe failed, add suspect node to dead node list: {}.",
probe.getDatanodeInfo());
addToDead(probe.getDatanodeInfo());
}
}
}
/**
* Check dead node periodically.
*/
private void checkDeadNodes() {
Set datanodeInfos = clearAndGetDetectedDeadNodes();
for (DatanodeInfo datanodeInfo : datanodeInfos) {
if (!deadNodesProbeQueue.offer(datanodeInfo)) {
LOG.debug("Skip to add dead node {} to check " +
"since the node is already in the probe queue.", datanodeInfo);
} else {
LOG.debug("Add dead node to check: {}.", datanodeInfo);
}
}
state = State.IDLE;
}
private void idle() {
try {
Thread.sleep(idleSleepMs);
} catch (InterruptedException e) {
LOG.debug("Got interrupted while DeadNodeDetector is idle.", e);
Thread.currentThread().interrupt();
}
state = State.CHECK_DEAD;
}
private void init() {
state = State.CHECK_DEAD;
}
private void addToDead(DatanodeInfo datanodeInfo) {
deadNodes.put(datanodeInfo.getDatanodeUuid(), datanodeInfo);
}
public boolean isDeadNode(DatanodeInfo datanodeInfo) {
return deadNodes.containsKey(datanodeInfo.getDatanodeUuid());
}
private void removeFromDead(DatanodeInfo datanodeInfo) {
deadNodes.remove(datanodeInfo.getDatanodeUuid());
}
public UniqueQueue getDeadNodesProbeQueue() {
return deadNodesProbeQueue;
}
public UniqueQueue getSuspectNodesProbeQueue() {
return suspectNodesProbeQueue;
}
@VisibleForTesting
void setSuspectQueue(UniqueQueue queue) {
this.suspectNodesProbeQueue = queue;
}
@VisibleForTesting
void setDeadQueue(UniqueQueue queue) {
this.deadNodesProbeQueue = queue;
}
/**
* Add datanode to suspectNodes and suspectAndDeadNodes.
*/
public synchronized void addNodeToDetect(DFSInputStream dfsInputStream,
DatanodeInfo datanodeInfo) {
HashSet datanodeInfos =
suspectAndDeadNodes.get(dfsInputStream);
if (datanodeInfos == null) {
datanodeInfos = new HashSet();
datanodeInfos.add(datanodeInfo);
suspectAndDeadNodes.putIfAbsent(dfsInputStream, datanodeInfos);
} else {
datanodeInfos.add(datanodeInfo);
}
LOG.debug("Add datanode {} to suspectAndDeadNodes.", datanodeInfo);
addSuspectNodeToDetect(datanodeInfo);
}
/**
* Add datanode to suspectNodes.
*/
private boolean addSuspectNodeToDetect(DatanodeInfo datanodeInfo) {
return suspectNodesProbeQueue.offer(datanodeInfo);
}
/**
* Remove dead node which is not used by any DFSInputStream from deadNodes.
* @return new dead node shared by all DFSInputStreams.
*/
public synchronized Set clearAndGetDetectedDeadNodes() {
// remove the dead nodes who doesn't have any inputstream first
Set newDeadNodes = new HashSet();
for (HashSet datanodeInfos : suspectAndDeadNodes.values()) {
newDeadNodes.addAll(datanodeInfos);
}
for (DatanodeInfo datanodeInfo : deadNodes.values()) {
if (!newDeadNodes.contains(datanodeInfo)) {
deadNodes.remove(datanodeInfo.getDatanodeUuid());
}
}
return new HashSet<>(deadNodes.values());
}
/**
* Remove suspect and dead node from suspectAndDeadNodes#dfsInputStream and
* local deadNodes.
*/
public synchronized void removeNodeFromDeadNodeDetector(
DFSInputStream dfsInputStream, DatanodeInfo datanodeInfo) {
Set datanodeInfos = suspectAndDeadNodes.get(dfsInputStream);
if (datanodeInfos != null) {
datanodeInfos.remove(datanodeInfo);
dfsInputStream.removeFromLocalDeadNodes(datanodeInfo);
if (datanodeInfos.isEmpty()) {
suspectAndDeadNodes.remove(dfsInputStream);
}
}
}
/**
* Remove suspect and dead node from suspectAndDeadNodes#dfsInputStream and
* local deadNodes.
*/
private synchronized void removeNodeFromDeadNodeDetector(
DatanodeInfo datanodeInfo) {
for (Map.Entry> entry :
suspectAndDeadNodes.entrySet()) {
Set datanodeInfos = entry.getValue();
if (datanodeInfos.remove(datanodeInfo)) {
DFSInputStream dfsInputStream = entry.getKey();
dfsInputStream.removeFromLocalDeadNodes(datanodeInfo);
if (datanodeInfos.isEmpty()) {
suspectAndDeadNodes.remove(dfsInputStream);
}
}
}
}
/**
* Remove suspect and dead node from suspectAndDeadNodes#dfsInputStream and
* deadNodes.
*/
private void removeDeadNode(DatanodeInfo datanodeInfo) {
removeNodeFromDeadNodeDetector(datanodeInfo);
removeFromDead(datanodeInfo);
}
private static void probeSleep(long time) {
try {
Thread.sleep(time);
} catch (InterruptedException e) {
LOG.debug("Got interrupted while probe is scheduling.", e);
Thread.currentThread().interrupt();
return;
}
}
/**
* Schedule probe data node.
*/
static class ProbeScheduler implements Runnable {
private DeadNodeDetector deadNodeDetector;
private ProbeType type;
ProbeScheduler(DeadNodeDetector deadNodeDetector, ProbeType type) {
this.deadNodeDetector = deadNodeDetector;
this.type = type;
}
@Override
public void run() {
while (!Thread.currentThread().isInterrupted()) {
deadNodeDetector.scheduleProbe(type);
if (type == ProbeType.CHECK_SUSPECT) {
probeSleep(deadNodeDetector.suspectNodeDetectInterval);
} else {
probeSleep(deadNodeDetector.deadNodeDetectInterval);
}
}
}
}
}