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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.server.datanode;
import java.io.IOException;
import java.net.SocketTimeoutException;
import java.nio.channels.AsynchronousCloseException;
import java.util.HashMap;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.net.Peer;
import org.apache.hadoop.hdfs.net.PeerServer;
import org.apache.hadoop.hdfs.util.DataTransferThrottler;
import org.apache.hadoop.util.Daemon;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import org.slf4j.Logger;
/**
* Server used for receiving/sending a block of data. This is created to listen
* for requests from clients or other DataNodes. This small server does not use
* the Hadoop IPC mechanism.
*/
class DataXceiverServer implements Runnable {
public static final Logger LOG = DataNode.LOG;
/**
* Default time to wait (in seconds) for the number of running threads to drop
* below the newly requested maximum before giving up.
*/
private static final int DEFAULT_RECONFIGURE_WAIT = 30;
private final PeerServer peerServer;
private final DataNode datanode;
private final HashMap peers = new HashMap<>();
private final HashMap peersXceiver = new HashMap<>();
private final Lock lock = new ReentrantLock();
private final Condition noPeers = lock.newCondition();
private boolean closed = false;
private int maxReconfigureWaitTime = DEFAULT_RECONFIGURE_WAIT;
/**
* Maximal number of concurrent xceivers per node.
* Enforcing the limit is required in order to avoid data-node
* running out of memory.
*/
int maxXceiverCount =
DFSConfigKeys.DFS_DATANODE_MAX_RECEIVER_THREADS_DEFAULT;
/**
* A manager to make sure that cluster balancing does not take too much
* resources.
*
* It limits the number of block moves for balancing and the total amount of
* bandwidth they can use.
*/
static class BlockBalanceThrottler extends DataTransferThrottler {
private final Semaphore semaphore;
private int maxThreads;
/**
* Constructor.
*
* @param bandwidth Total amount of bandwidth can be used for balancing
*/
private BlockBalanceThrottler(long bandwidth, int maxThreads) {
super(bandwidth);
this.semaphore = new Semaphore(maxThreads, true);
this.maxThreads = maxThreads;
LOG.info("Balancing bandwidth is " + bandwidth + " bytes/s");
LOG.info("Number threads for balancing is " + maxThreads);
}
/**
* Update the number of threads which may be used concurrently for moving
* blocks. The number of threads available can be scaled up or down. If
* increasing the number of threads, the request will be serviced
* immediately. However, if decreasing the number of threads, this method
* will block any new request for moves, wait for any existing backlog of
* move requests to clear, and wait for enough threads to have finished such
* that the total number of threads actively running is less than or equal
* to the new cap. If this method has been unable to successfully set the
* new, lower, cap within 'duration' seconds, the attempt will be aborted
* and the original cap will remain.
*
* @param newMaxThreads The new maximum number of threads for block moving
* @param duration The number of seconds to wait if decreasing threads
* @return true if new maximum was successfully applied; false otherwise
*/
private boolean setMaxConcurrentMovers(final int newMaxThreads,
final int duration) {
Preconditions.checkArgument(newMaxThreads > 0);
final int delta = newMaxThreads - this.maxThreads;
LOG.debug("Change concurrent thread count to {} from {}", newMaxThreads,
this.maxThreads);
if (delta == 0) {
return true;
}
if (delta > 0) {
LOG.debug("Adding thread capacity: {}", delta);
this.semaphore.release(delta);
this.maxThreads = newMaxThreads;
return true;
}
try {
LOG.debug("Removing thread capacity: {}. Max wait: {}", delta,
duration);
boolean acquired = this.semaphore.tryAcquire(Math.abs(delta), duration,
TimeUnit.SECONDS);
if (acquired) {
this.maxThreads = newMaxThreads;
} else {
LOG.warn("Could not lower thread count to {} from {}. Too busy.",
newMaxThreads, this.maxThreads);
}
return acquired;
} catch (InterruptedException e) {
LOG.warn("Interrupted before adjusting thread count: {}", delta);
return false;
}
}
@VisibleForTesting
int getMaxConcurrentMovers() {
return this.maxThreads;
}
/**
* Check if the block move can start
*
* Return true if the thread quota is not exceeded and
* the counter is incremented; False otherwise.
*/
boolean acquire() {
return this.semaphore.tryAcquire();
}
/**
* Mark that the move is completed. The thread counter is decremented.
*/
void release() {
this.semaphore.release();
}
}
final BlockBalanceThrottler balanceThrottler;
private final DataTransferThrottler transferThrottler;
private final DataTransferThrottler writeThrottler;
/**
* Stores an estimate for block size to check if the disk partition has enough
* space. Newer clients pass the expected block size to the DataNode. For
* older clients, just use the server-side default block size.
*/
final long estimateBlockSize;
DataXceiverServer(PeerServer peerServer, Configuration conf,
DataNode datanode) {
this.peerServer = peerServer;
this.datanode = datanode;
this.maxXceiverCount =
conf.getInt(DFSConfigKeys.DFS_DATANODE_MAX_RECEIVER_THREADS_KEY,
DFSConfigKeys.DFS_DATANODE_MAX_RECEIVER_THREADS_DEFAULT);
this.estimateBlockSize = conf.getLongBytes(DFSConfigKeys.DFS_BLOCK_SIZE_KEY,
DFSConfigKeys.DFS_BLOCK_SIZE_DEFAULT);
//set up parameter for cluster balancing
this.balanceThrottler = new BlockBalanceThrottler(
conf.getLongBytes(DFSConfigKeys.DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY,
DFSConfigKeys.DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_DEFAULT),
conf.getInt(DFSConfigKeys.DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_KEY,
DFSConfigKeys.DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_DEFAULT));
long bandwidthPerSec = conf.getLongBytes(
DFSConfigKeys.DFS_DATANODE_DATA_TRANSFER_BANDWIDTHPERSEC_KEY,
DFSConfigKeys.DFS_DATANODE_DATA_TRANSFER_BANDWIDTHPERSEC_DEFAULT);
if (bandwidthPerSec > 0) {
this.transferThrottler = new DataTransferThrottler(bandwidthPerSec);
} else {
this.transferThrottler = null;
}
bandwidthPerSec = conf.getLongBytes(
DFSConfigKeys.DFS_DATANODE_DATA_WRITE_BANDWIDTHPERSEC_KEY,
DFSConfigKeys.DFS_DATANODE_DATA_WRITE_BANDWIDTHPERSEC_DEFAULT);
if (bandwidthPerSec > 0) {
this.writeThrottler = new DataTransferThrottler(bandwidthPerSec);
} else {
this.writeThrottler = null;
}
}
@Override
public void run() {
Peer peer = null;
while (datanode.shouldRun && !datanode.shutdownForUpgrade) {
try {
peer = peerServer.accept();
// Make sure the xceiver count is not exceeded
int curXceiverCount = datanode.getXceiverCount();
if (curXceiverCount > maxXceiverCount) {
throw new IOException("Xceiver count " + curXceiverCount
+ " exceeds the limit of concurrent xcievers: "
+ maxXceiverCount);
}
new Daemon(datanode.threadGroup,
DataXceiver.create(peer, datanode, this))
.start();
} catch (SocketTimeoutException ignored) {
// wake up to see if should continue to run
} catch (AsynchronousCloseException ace) {
// another thread closed our listener socket - that's expected during shutdown,
// but not in other circumstances
if (datanode.shouldRun && !datanode.shutdownForUpgrade) {
LOG.warn("{}:DataXceiverServer", datanode.getDisplayName(), ace);
}
} catch (IOException ie) {
IOUtils.closeQuietly(peer);
LOG.warn("{}:DataXceiverServer", datanode.getDisplayName(), ie);
} catch (OutOfMemoryError ie) {
IOUtils.closeQuietly(peer);
// DataNode can run out of memory if there is too many transfers.
// Log the event, Sleep for 30 seconds, other transfers may complete by
// then.
LOG.error("DataNode is out of memory. Will retry in 30 seconds.", ie);
try {
Thread.sleep(TimeUnit.SECONDS.toMillis(30L));
} catch (InterruptedException e) {
// ignore
}
} catch (Throwable te) {
LOG.error("{}:DataXceiverServer: Exiting.", datanode.getDisplayName(),
te);
datanode.shouldRun = false;
}
}
// Close the server to stop reception of more requests.
lock.lock();
try {
if (!closed) {
peerServer.close();
closed = true;
}
} catch (IOException ie) {
LOG.warn("{}:DataXceiverServer: close exception",
datanode.getDisplayName(), ie);
} finally {
lock.unlock();
}
// if in restart prep stage, notify peers before closing them.
if (datanode.shutdownForUpgrade) {
restartNotifyPeers();
// Each thread needs some time to process it. If a thread needs
// to send an OOB message to the client, but blocked on network for
// long time, we need to force its termination.
LOG.info("Shutting down DataXceiverServer before restart");
waitAllPeers(2L, TimeUnit.SECONDS);
}
closeAllPeers();
}
void kill() {
assert (datanode.shouldRun == false || datanode.shutdownForUpgrade) :
"shoudRun should be set to false or restarting should be true"
+ " before killing";
lock.lock();
try {
if (!closed) {
peerServer.close();
closed = true;
}
} catch (IOException ie) {
LOG.warn("{}:DataXceiverServer.kill()", datanode.getDisplayName(), ie);
} finally {
lock.unlock();
}
}
void addPeer(Peer peer, Thread t, DataXceiver xceiver)
throws IOException {
lock.lock();
try {
if (closed) {
throw new IOException("Server closed.");
}
peers.put(peer, t);
peersXceiver.put(peer, xceiver);
datanode.metrics.incrDataNodeActiveXceiversCount();
} finally {
lock.unlock();
}
}
void closePeer(Peer peer) {
lock.lock();
try {
peers.remove(peer);
peersXceiver.remove(peer);
datanode.metrics.decrDataNodeActiveXceiversCount();
IOUtils.closeQuietly(peer);
if (peers.isEmpty()) {
this.noPeers.signalAll();
}
} finally {
lock.unlock();
}
}
// Sending OOB to all peers
public void sendOOBToPeers() {
lock.lock();
try {
if (!datanode.shutdownForUpgrade) {
return;
}
for (Peer p : peers.keySet()) {
try {
peersXceiver.get(p).sendOOB();
} catch (IOException e) {
LOG.warn("Got error when sending OOB message.", e);
} catch (InterruptedException e) {
LOG.warn("Interrupted when sending OOB message.");
}
}
} finally {
lock.unlock();
}
}
public void stopWriters() {
lock.lock();
try {
peers.keySet().forEach(p -> peersXceiver.get(p).stopWriter());
} finally {
lock.unlock();
}
}
/**
* Notify all peers of the shutdown and restart. 'datanode.shouldRun' should
* still be true and 'datanode.restarting' should be set true before calling
* this method.
*/
void restartNotifyPeers() {
assert (datanode.shouldRun && datanode.shutdownForUpgrade);
lock.lock();
try {
// interrupt each and every DataXceiver thread.
peers.values().forEach(t -> t.interrupt());
} finally {
lock.unlock();
}
}
/**
* Close all peers and clear the map.
*/
void closeAllPeers() {
LOG.info("Closing all peers.");
lock.lock();
try {
peers.keySet().forEach(p -> IOUtils.closeQuietly(p));
peers.clear();
peersXceiver.clear();
datanode.metrics.setDataNodeActiveXceiversCount(0);
this.noPeers.signalAll();
} finally {
lock.unlock();
}
}
/**
* Causes a thread to block until all peers are removed, a certain amount of
* time has passed, or the thread is interrupted.
*
* @param timeout the maximum time to wait, in nanoseconds
* @param unit the unit of time to wait
* @return true if thread returned because all peers were removed; false
* otherwise
*/
private boolean waitAllPeers(long timeout, TimeUnit unit) {
long nanos = unit.toNanos(timeout);
lock.lock();
try {
while (!peers.isEmpty()) {
if (nanos <= 0L) {
return false;
}
nanos = noPeers.awaitNanos(nanos);
}
} catch (InterruptedException e) {
LOG.debug("Interrupted waiting for peers to close");
return false;
} finally {
lock.unlock();
}
return true;
}
/**
* Return the number of peers.
*
* @return the number of active peers
*/
int getNumPeers() {
lock.lock();
try {
return peers.size();
} finally {
lock.unlock();
}
}
/**
* Return the number of peers and DataXceivers.
*
* @return the number of peers and DataXceivers.
*/
@VisibleForTesting
int getNumPeersXceiver() {
lock.lock();
try {
return peersXceiver.size();
} finally {
lock.unlock();
}
}
@VisibleForTesting
PeerServer getPeerServer() {
return peerServer;
}
public DataTransferThrottler getTransferThrottler() {
return transferThrottler;
}
public DataTransferThrottler getWriteThrottler() {
return writeThrottler;
}
/**
* Release a peer.
*
* @param peer The peer to release
*/
void releasePeer(Peer peer) {
lock.lock();
try {
peers.remove(peer);
peersXceiver.remove(peer);
datanode.metrics.decrDataNodeActiveXceiversCount();
} finally {
lock.unlock();
}
}
/**
* Update the number of threads which may be used concurrently for moving
* blocks.
*
* @param movers The new maximum number of threads for block moving
* @return true if new maximum was successfully applied; false otherwise
*/
public boolean updateBalancerMaxConcurrentMovers(final int movers) {
return balanceThrottler.setMaxConcurrentMovers(movers,
this.maxReconfigureWaitTime);
}
/**
* Update the maximum amount of time to wait for reconfiguration of the
* maximum number of block mover threads to complete.
*
* @param max The new maximum number of threads for block moving, in seconds
*/
@VisibleForTesting
void setMaxReconfigureWaitTime(int max) {
this.maxReconfigureWaitTime = max;
}
}
