HDFS-12976. [SBN read] Introduce ObserverReadProxyProvider. Contributed by Chao Sun.

This commit is contained in:
Chao Sun 2018-07-11 16:01:05 -07:00 committed by Konstantin V Shvachko
parent 0105d7f597
commit 64b7cf59bd
7 changed files with 635 additions and 2 deletions

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@ -448,4 +448,9 @@ public class RetryInvocationHandler<T> implements RpcInvocationHandler {
public ConnectionId getConnectionId() { public ConnectionId getConnectionId() {
return RPC.getConnectionIdForProxy(proxyDescriptor.getProxy()); return RPC.getConnectionIdForProxy(proxyDescriptor.getProxy());
} }
@VisibleForTesting
public FailoverProxyProvider<T> getProxyProvider() {
return proxyDescriptor.fpp;
}
} }

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@ -34,7 +34,7 @@ import java.util.concurrent.atomic.LongAccumulator;
*/ */
@InterfaceAudience.Private @InterfaceAudience.Private
@InterfaceStability.Stable @InterfaceStability.Stable
class ClientGSIContext implements AlignmentContext { public class ClientGSIContext implements AlignmentContext {
private final LongAccumulator lastSeenStateId = private final LongAccumulator lastSeenStateId =
new LongAccumulator(Math::max, Long.MIN_VALUE); new LongAccumulator(Math::max, Long.MIN_VALUE);

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@ -0,0 +1,273 @@
/**
* 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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.namenode.ha;
import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.hdfs.ClientGSIContext;
import org.apache.hadoop.hdfs.NameNodeProxiesClient;
import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
import com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.ipc.AlignmentContext;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.ipc.StandbyException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A {@link org.apache.hadoop.io.retry.FailoverProxyProvider} implementation
* that supports reading from observer namenode(s).
*
* This constructs a wrapper proxy that sends the request to observer
* namenode(s), if observer read is enabled. In case there are multiple
* observer namenodes, it will try them one by one in case the RPC failed. It
* will fail back to the active namenode after it has exhausted all the
* observer namenodes.
*
* Read and write requests will still be sent to active NN if reading from
* observer is turned off.
*/
public class ObserverReadProxyProvider<T extends ClientProtocol>
extends ConfiguredFailoverProxyProvider<T> {
private static final Logger LOG = LoggerFactory.getLogger(
ObserverReadProxyProvider.class);
/** Client-side context for syncing with the NameNode server side */
private AlignmentContext alignmentContext;
/** Proxies for the observer namenodes */
private final List<AddressRpcProxyPair<T>> observerProxies =
new ArrayList<>();
/**
* Whether reading from observer is enabled. If this is false, all read
* requests will still go to active NN.
*/
private boolean observerReadEnabled;
/**
* Thread-local index to record the current index in the observer list.
*/
private static final ThreadLocal<Integer> currentIndex =
ThreadLocal.withInitial(() -> 0);
/** The last proxy that has been used. Only used for testing */
private volatile ProxyInfo<T> lastProxy = null;
@SuppressWarnings("unchecked")
public ObserverReadProxyProvider(
Configuration conf, URI uri, Class<T> xface, HAProxyFactory<T> factory)
throws IOException {
super(conf, uri, xface, factory);
alignmentContext = new ClientGSIContext();
((ClientHAProxyFactory<T>) factory).setAlignmentContext(alignmentContext);
// Find out all the observer proxies
for (AddressRpcProxyPair<T> ap : this.proxies) {
ap.namenode = (T) NameNodeProxiesClient.createProxyWithAlignmentContext(
ap.address, conf, ugi, false, getFallbackToSimpleAuth(),
alignmentContext);
if (isObserverState(ap)) {
observerProxies.add(ap);
}
}
if (observerProxies.isEmpty()) {
throw new RuntimeException("Couldn't find any namenode proxy in " +
"OBSERVER state");
}
// Randomize the list to prevent all clients pointing to the same one
boolean randomized = conf.getBoolean(
HdfsClientConfigKeys.Failover.RANDOM_ORDER,
HdfsClientConfigKeys.Failover.RANDOM_ORDER_DEFAULT);
if (randomized) {
Collections.shuffle(observerProxies);
}
}
@Override
public synchronized AlignmentContext getAlignmentContext() {
return alignmentContext;
}
@SuppressWarnings("unchecked")
@Override
public synchronized ProxyInfo<T> getProxy() {
// We just create a wrapped proxy containing all the proxies
List<ProxyInfo<T>> observerProxies = new ArrayList<>();
StringBuilder combinedInfo = new StringBuilder("[");
for (int i = 0; i < this.observerProxies.size(); i++) {
if (i > 0) {
combinedInfo.append(",");
}
AddressRpcProxyPair<T> p = this.observerProxies.get(i);
ProxyInfo<T> pInfo = getProxy(p);
observerProxies.add(pInfo);
combinedInfo.append(pInfo.proxyInfo);
}
combinedInfo.append(']');
T wrappedProxy = (T) Proxy.newProxyInstance(
ObserverReadInvocationHandler.class.getClassLoader(),
new Class<?>[]{xface},
new ObserverReadInvocationHandler(observerProxies));
return new ProxyInfo<>(wrappedProxy, combinedInfo.toString());
}
/**
* Check if a method is read-only.
*
* @return whether the 'method' is a read-only operation.
*/
private boolean isRead(Method method) {
return method.isAnnotationPresent(ReadOnly.class);
}
@VisibleForTesting
void setObserverReadEnabled(boolean flag) {
this.observerReadEnabled = flag;
}
/**
* After getting exception 'ex', whether we should retry the current request
* on a different observer.
*/
private boolean shouldRetry(Exception ex) throws Exception {
// TODO: implement retry policy
return true;
}
@VisibleForTesting
ProxyInfo<T> getLastProxy() {
return lastProxy;
}
boolean isObserverState(AddressRpcProxyPair<T> ap) {
// TODO: should introduce new ClientProtocol method to verify the
// underlying service state, which does not require superuser access
// The is a workaround
IOException ioe = null;
try {
// Verify write access first
ap.namenode.reportBadBlocks(new LocatedBlock[0]);
return false; // Only active NameNode allows write
} catch (RemoteException re) {
IOException sbe = re.unwrapRemoteException(StandbyException.class);
if (!(sbe instanceof StandbyException)) {
ioe = re;
}
} catch (IOException e) {
ioe = e;
}
if (ioe != null) {
LOG.error("Failed to connect to {}", ap.address, ioe);
return false;
}
// Verify read access
// For now we assume only Observer nodes allow reads
// Stale reads on StandbyNode should be turned off
try {
ap.namenode.checkAccess("/", FsAction.READ);
return true;
} catch (RemoteException re) {
IOException sbe = re.unwrapRemoteException(StandbyException.class);
if (!(sbe instanceof StandbyException)) {
ioe = re;
}
} catch (IOException e) {
ioe = e;
}
if (ioe != null) {
LOG.error("Failed to connect to {}", ap.address, ioe);
}
return false;
}
class ObserverReadInvocationHandler implements InvocationHandler {
final List<ProxyInfo<T>> observerProxies;
final ProxyInfo<T> activeProxy;
ObserverReadInvocationHandler(List<ProxyInfo<T>> observerProxies) {
this.observerProxies = observerProxies;
this.activeProxy = ObserverReadProxyProvider.super.getProxy();
}
/**
* Sends read operations to the observer (if enabled) specified by the
* current index, and send write operations to the active. If a observer
* fails, we increment the index and retry the next one. If all observers
* fail, the request is forwarded to the active.
*
* Write requests are always forwarded to the active.
*/
@Override
public Object invoke(Object proxy, final Method method, final Object[] args)
throws Throwable {
lastProxy = null;
Object retVal;
if (observerReadEnabled && isRead(method)) {
// Loop through all the proxies, starting from the current index.
for (int i = 0; i < observerProxies.size(); i++) {
ProxyInfo<T> current = observerProxies.get(currentIndex.get());
try {
retVal = method.invoke(current.proxy, args);
lastProxy = current;
return retVal;
} catch (Exception e) {
if (!shouldRetry(e)) {
throw e;
}
currentIndex.set((currentIndex.get() + 1) % observerProxies.size());
LOG.warn("Invocation returned exception on [{}]",
current.proxyInfo, e.getCause());
}
}
// If we get here, it means all observers have failed.
LOG.warn("All observers have failed for read request {}. " +
"Fall back on active: {}", method.getName(), activeProxy);
}
// Either all observers have failed, or that it is a write request.
// In either case, we'll forward the request to active NameNode.
try {
retVal = method.invoke(activeProxy.proxy, args);
} catch (Exception e) {
throw e.getCause();
}
lastProxy = activeProxy;
return retVal;
}
}
}

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@ -2646,6 +2646,12 @@ public class MiniDFSCluster implements AutoCloseable {
getNameNode(nnIndex).getRpcServer().transitionToStandby( getNameNode(nnIndex).getRpcServer().transitionToStandby(
new StateChangeRequestInfo(RequestSource.REQUEST_BY_USER_FORCED)); new StateChangeRequestInfo(RequestSource.REQUEST_BY_USER_FORCED));
} }
public void transitionToObserver(int nnIndex) throws IOException,
ServiceFailedException {
getNameNode(nnIndex).getRpcServer().transitionToObserver(
new StateChangeRequestInfo(RequestSource.REQUEST_BY_USER_FORCED));
}
public void triggerBlockReports() public void triggerBlockReports()

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@ -90,7 +90,7 @@ public class TestStateAlignmentContextWithHA {
// Create and set AlignmentContext in HAProxyFactory. // Create and set AlignmentContext in HAProxyFactory.
// All proxies by factory will now have AlignmentContext assigned. // All proxies by factory will now have AlignmentContext assigned.
this.alignmentContext = (spy != null ? spy : new ClientGSIContext()); this.alignmentContext = (spy != null ? spy : new ClientGSIContext());
((ClientHAProxyFactory) factory).setAlignmentContext(alignmentContext); ((ClientHAProxyFactory<T>) factory).setAlignmentContext(alignmentContext);
AC_LIST.add(alignmentContext); AC_LIST.add(alignmentContext);
} }

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@ -159,6 +159,18 @@ public abstract class HATestUtil {
return (DistributedFileSystem)fs; return (DistributedFileSystem)fs;
} }
public static DistributedFileSystem configureObserverReadFs(
MiniDFSCluster cluster, Configuration conf,
int nsIndex) throws IOException, URISyntaxException {
conf = new Configuration(conf);
String logicalName = getLogicalHostname(cluster);
setFailoverConfigurations(cluster, conf, logicalName, nsIndex);
conf.set(HdfsClientConfigKeys.Failover.PROXY_PROVIDER_KEY_PREFIX + "." +
logicalName, ObserverReadProxyProvider.class.getName());
FileSystem fs = FileSystem.get(new URI("hdfs://" + logicalName), conf);
return (DistributedFileSystem) fs;
}
public static void setFailoverConfigurations(MiniDFSCluster cluster, public static void setFailoverConfigurations(MiniDFSCluster cluster,
Configuration conf) { Configuration conf) {
setFailoverConfigurations(cluster, conf, getLogicalHostname(cluster)); setFailoverConfigurations(cluster, conf, getLogicalHostname(cluster));

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@ -0,0 +1,337 @@
/**
* 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
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* 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.namenode.ha;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.qjournal.MiniQJMHACluster;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
import org.apache.hadoop.io.retry.FailoverProxyProvider;
import org.apache.hadoop.io.retry.RetryInvocationHandler;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.Proxy;
import java.net.URI;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
// Main unit tests for ObserverNode
public class TestObserverNode {
private Configuration conf;
private MiniQJMHACluster qjmhaCluster;
private MiniDFSCluster dfsCluster;
private NameNode[] namenodes;
private Path testPath;
private Path testPath2;
private Path testPath3;
/** These are set in each individual test case */
private DistributedFileSystem dfs;
private ObserverReadProxyProvider<?> provider;
@Before
public void setUp() throws Exception {
conf = new Configuration();
setUpCluster(1);
testPath = new Path("/test");
testPath2 = new Path("/test2");
testPath3 = new Path("/test3");
}
@After
public void cleanUp() throws IOException {
if (qjmhaCluster != null) {
qjmhaCluster.shutdown();
}
}
@Test
public void testSimpleRead() throws Exception {
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
assertSentTo(0);
try {
dfs.getFileStatus(testPath);
fail("Should throw FileNotFoundException");
} catch (FileNotFoundException e) {
// Pass
}
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentTo(2);
dfs.mkdir(testPath2, FsPermission.getDefault());
assertSentTo(0);
}
@Test
public void testFailover() throws Exception {
setObserverRead(false);
dfs.mkdir(testPath, FsPermission.getDefault());
assertSentTo(0);
dfs.getFileStatus(testPath);
assertSentTo(0);
dfsCluster.transitionToStandby(0);
dfsCluster.transitionToActive(1);
dfsCluster.waitActive();
dfs.mkdir(testPath2, FsPermission.getDefault());
assertSentTo(1);
dfs.getFileStatus(testPath);
assertSentTo(1);
}
@Test
public void testDoubleFailover() throws Exception {
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
assertSentTo(0);
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentTo(2);
dfs.mkdir(testPath2, FsPermission.getDefault());
assertSentTo(0);
dfsCluster.transitionToStandby(0);
dfsCluster.transitionToActive(1);
dfsCluster.waitActive(1);
rollEditLogAndTail(1);
dfs.getFileStatus(testPath2);
assertSentTo(2);
dfs.mkdir(testPath3, FsPermission.getDefault());
assertSentTo(1);
dfsCluster.transitionToStandby(1);
dfsCluster.transitionToActive(0);
dfsCluster.waitActive(0);
rollEditLogAndTail(0);
dfs.getFileStatus(testPath3);
assertSentTo(2);
dfs.delete(testPath3, false);
assertSentTo(0);
}
@Test
public void testObserverFailover() throws Exception {
setUpCluster(2);
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentToAny(2, 3);
// Transition observer #2 to standby, request should go to the #3.
dfsCluster.transitionToStandby(2);
dfs.getFileStatus(testPath);
assertSentTo(3);
// Transition observer #3 to standby, request should go to active
dfsCluster.transitionToStandby(3);
dfs.getFileStatus(testPath);
assertSentTo(0);
// Transition #2 back to observer, request should go to #2
dfsCluster.transitionToObserver(2);
dfs.getFileStatus(testPath);
assertSentTo(2);
// Transition #3 back to observer, request should go to either #2 or #3
dfsCluster.transitionToObserver(3);
dfs.getFileStatus(testPath);
assertSentToAny(2, 3);
}
@Test
public void testObserverShutdown() throws Exception {
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentTo(2);
// Shutdown the observer - requests should go to active
dfsCluster.shutdownNameNode(2);
dfs.getFileStatus(testPath);
assertSentTo(0);
// Start the observer again - requests should go to observer
dfsCluster.restartNameNode(2);
dfsCluster.transitionToObserver(2);
dfs.getFileStatus(testPath);
assertSentTo(2);
}
@Test
public void testObserverFailOverAndShutdown() throws Exception {
// Test the case when there is a failover before ONN shutdown
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentTo(2);
dfsCluster.transitionToStandby(0);
dfsCluster.transitionToActive(1);
dfsCluster.waitActive();
// Shutdown the observer - requests should go to active
dfsCluster.shutdownNameNode(2);
dfs.getFileStatus(testPath);
assertSentTo(1);
// Start the observer again - requests should go to observer
dfsCluster.restartNameNode(2);
dfs.getFileStatus(testPath);
assertSentTo(1);
dfsCluster.transitionToObserver(2);
dfs.getFileStatus(testPath);
assertSentTo(2);
}
@Test
public void testMultiObserver() throws Exception {
setUpCluster(2);
setObserverRead(true);
dfs.mkdir(testPath, FsPermission.getDefault());
assertSentTo(0);
rollEditLogAndTail(0);
dfs.getFileStatus(testPath);
assertSentToAny(2, 3);
dfs.mkdir(testPath2, FsPermission.getDefault());
rollEditLogAndTail(0);
// Shutdown first observer, request should go to the second one
dfsCluster.shutdownNameNode(2);
dfs.listStatus(testPath2);
assertSentTo(3);
// Restart the first observer
dfsCluster.restartNameNode(2);
dfs.listStatus(testPath);
assertSentTo(3);
dfsCluster.transitionToObserver(2);
dfs.listStatus(testPath);
assertSentToAny(2, 3);
dfs.mkdir(testPath3, FsPermission.getDefault());
rollEditLogAndTail(0);
// Now shutdown the second observer, request should go to the first one
dfsCluster.shutdownNameNode(3);
dfs.listStatus(testPath3);
assertSentTo(2);
// Shutdown both, request should go to active
dfsCluster.shutdownNameNode(2);
dfs.listStatus(testPath3);
assertSentTo(0);
}
@Test
public void testBootstrap() throws Exception {
for (URI u : dfsCluster.getNameDirs(2)) {
File dir = new File(u.getPath());
assertTrue(FileUtil.fullyDelete(dir));
}
int rc = BootstrapStandby.run(
new String[]{"-nonInteractive"},
dfsCluster.getConfiguration(2)
);
assertEquals(0, rc);
}
private void setUpCluster(int numObservers) throws Exception {
qjmhaCluster = new MiniQJMHACluster.Builder(conf)
.setNumNameNodes(2 + numObservers)
.build();
dfsCluster = qjmhaCluster.getDfsCluster();
namenodes = new NameNode[2 + numObservers];
for (int i = 0; i < namenodes.length; i++) {
namenodes[i] = dfsCluster.getNameNode(i);
}
dfsCluster.transitionToActive(0);
dfsCluster.waitActive(0);
for (int i = 0; i < numObservers; i++) {
dfsCluster.transitionToObserver(2 + i);
}
}
private void assertSentTo(int nnIdx) {
assertSentToAny(nnIdx);
}
private void assertSentToAny(int... nnIndices) {
FailoverProxyProvider.ProxyInfo<?> pi = provider.getLastProxy();
for (int nnIdx : nnIndices) {
if (pi.proxyInfo.equals(
dfsCluster.getNameNode(nnIdx).getNameNodeAddress().toString())) {
return;
}
}
fail("Request was not sent to any of the expected namenodes");
}
private void setObserverRead(boolean flag) throws Exception {
dfs = HATestUtil.configureObserverReadFs(dfsCluster, conf, 0);
RetryInvocationHandler<?> handler =
(RetryInvocationHandler<?>) Proxy.getInvocationHandler(
dfs.getClient().getNamenode());
provider = (ObserverReadProxyProvider<?>) handler.getProxyProvider();
provider.setObserverReadEnabled(flag);
}
private void rollEditLogAndTail(int indexForActiveNN) throws Exception {
dfsCluster.getNameNode(indexForActiveNN).getRpcServer().rollEditLog();
for (int i = 2; i < namenodes.length; i++) {
dfsCluster.getNameNode(i).getNamesystem().getEditLogTailer()
.doTailEdits();
}
}
}