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HDFS-9574. Reduce client failures during datanode restart. Contributed by Kihwal Lee.

This commit is contained in:
Kihwal Lee 2016-01-08 11:31:49 -06:00
parent 5dc5bb2812
commit b06e39de4f
9 changed files with 231 additions and 63 deletions
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2
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -14,6 +14,8 @@ Release 2.7.3 - UNRELEASED
HDFS-7163. WebHdfsFileSystem should retry reads according to the configured
retry policy. (Eric Payne via kihwal)
HDFS-9574. Reduce client failures during datanode restart (kihwal)
OPTIMIZATIONS
BUG FIXES

2
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
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@ -492,6 +492,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
public static final String DFS_DATANODE_MIN_SUPPORTED_NAMENODE_VERSION_KEY = "dfs.datanode.min.supported.namenode.version";
public static final String DFS_DATANODE_MIN_SUPPORTED_NAMENODE_VERSION_DEFAULT = "2.1.0-beta";
public static final String DFS_NAMENODE_INODE_ATTRIBUTES_PROVIDER_KEY = "dfs.namenode.inode.attributes.provider.class";
public static final String DFS_DATANODE_BP_READY_TIMEOUT_KEY = "dfs.datanode.bp-ready.timeout";
public static final long DFS_DATANODE_BP_READY_TIMEOUT_DEFAULT = 20;
public static final String DFS_BLOCK_ACCESS_TOKEN_ENABLE_KEY = "dfs.block.access.token.enable";
public static final boolean DFS_BLOCK_ACCESS_TOKEN_ENABLE_DEFAULT = false;

60
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
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@ -29,6 +29,7 @@ import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
@ -71,10 +72,12 @@ import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
import org.apache.hadoop.io.ByteBufferPool;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.ipc.RetriableException;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.IdentityHashStore;
import org.apache.hadoop.util.StopWatch;
import org.apache.htrace.Span;
import org.apache.htrace.Trace;
import org.apache.htrace.TraceScope;
@ -345,13 +348,19 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
private long readBlockLength(LocatedBlock locatedblock) throws IOException {
assert locatedblock != null : "LocatedBlock cannot be null";
int replicaNotFoundCount = locatedblock.getLocations().length;
for(DatanodeInfo datanode : locatedblock.getLocations()) {
final int timeout = dfsClient.getConf().socketTimeout;
LinkedList<DatanodeInfo> nodeList = new LinkedList<DatanodeInfo>(
Arrays.asList(locatedblock.getLocations()));
LinkedList<DatanodeInfo> retryList = new LinkedList<DatanodeInfo>();
boolean isRetry = false;
StopWatch sw = new StopWatch();
while (nodeList.size() > 0) {
DatanodeInfo datanode = nodeList.pop();
ClientDatanodeProtocol cdp = null;
try {
cdp = DFSUtil.createClientDatanodeProtocolProxy(datanode,
dfsClient.getConfiguration(), dfsClient.getConf().socketTimeout,
dfsClient.getConfiguration(), timeout,
dfsClient.getConf().connectToDnViaHostname, locatedblock);
final long n = cdp.getReplicaVisibleLength(locatedblock.getBlock());
@ -359,13 +368,18 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
if (n >= 0) {
return n;
}
}
catch(IOException ioe) {
if (ioe instanceof RemoteException &&
(((RemoteException) ioe).unwrapRemoteException() instanceof
ReplicaNotFoundException)) {
// special case : replica might not be on the DN, treat as 0 length
replicaNotFoundCount--;
} catch (IOException ioe) {
if (ioe instanceof RemoteException) {
if (((RemoteException) ioe).unwrapRemoteException() instanceof
ReplicaNotFoundException) {
// replica is not on the DN. We will treat it as 0 length
// if no one actually has a replica.
replicaNotFoundCount--;
} else if (((RemoteException) ioe).unwrapRemoteException() instanceof
RetriableException) {
// add to the list to be retried if necessary.
retryList.add(datanode);
}
}
if (DFSClient.LOG.isDebugEnabled()) {
@ -377,6 +391,30 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
RPC.stopProxy(cdp);
}
}
// Ran out of nodes, but there are retriable nodes.
if (nodeList.size() == 0 && retryList.size() > 0) {
nodeList.addAll(retryList);
retryList.clear();
isRetry = true;
}
if (isRetry) {
// start the stop watch if not already running.
if (!sw.isRunning()) {
sw.start();
}
try {
Thread.sleep(500); // delay between retries.
} catch (InterruptedException e) {
throw new IOException("Interrupted while getting the length.");
}
}
// see if we ran out of retry time
if (sw.isRunning() && sw.now(TimeUnit.MILLISECONDS) > timeout) {
break;
}
}
// Namenode told us about these locations, but none know about the replica

12
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java
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@ -50,6 +50,8 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_RESTART_REPLICA_
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT;
import static org.apache.hadoop.hdfs.DFSConfigKeys.IGNORE_SECURE_PORTS_FOR_TESTING_KEY;
import static org.apache.hadoop.hdfs.DFSConfigKeys.IGNORE_SECURE_PORTS_FOR_TESTING_DEFAULT;
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_BP_READY_TIMEOUT_KEY;
import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_BP_READY_TIMEOUT_DEFAULT;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
@ -100,6 +102,8 @@ public class DNConf {
final long maxLockedMemory;
private final long bpReadyTimeout;
public DNConf(Configuration conf) {
this.conf = conf;
socketTimeout = conf.getInt(DFS_CLIENT_SOCKET_TIMEOUT_KEY,
@ -193,6 +197,10 @@ public class DNConf {
this.restartReplicaExpiry = conf.getLong(
DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY,
DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT) * 1000L;
this.bpReadyTimeout = conf.getLong(
DFS_DATANODE_BP_READY_TIMEOUT_KEY,
DFS_DATANODE_BP_READY_TIMEOUT_DEFAULT);
}
// We get minimumNameNodeVersion via a method so it can be mocked out in tests.
@ -266,4 +274,8 @@ public class DNConf {
public boolean getIgnoreSecurePortsForTesting() {
return ignoreSecurePortsForTesting;
}
public long getBpReadyTimeout() {
return bpReadyTimeout;
}
}

11
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
View File

@ -1429,6 +1429,7 @@ public class DataNode extends ReconfigurableBase
@VisibleForTesting
public DatanodeRegistration getDNRegistrationForBP(String bpid)
throws IOException {
DataNodeFaultInjector.get().noRegistration();
BPOfferService bpos = blockPoolManager.get(bpid);
if(bpos==null || bpos.bpRegistration==null) {
throw new IOException("cannot find BPOfferService for bpid="+bpid);
@ -1556,7 +1557,6 @@ public class DataNode extends ReconfigurableBase
throw new ShortCircuitFdsUnsupportedException(
fileDescriptorPassingDisabledReason);
}
checkBlockToken(blk, token, BlockTokenSecretManager.AccessMode.READ);
int blkVersion = CURRENT_BLOCK_FORMAT_VERSION;
if (maxVersion < blkVersion) {
throw new ShortCircuitFdsVersionException("Your client is too old " +
@ -2798,6 +2798,15 @@ public class DataNode extends ReconfigurableBase
}
private void checkReadAccess(final ExtendedBlock block) throws IOException {
// Make sure this node has registered for the block pool.
try {
getDNRegistrationForBP(block.getBlockPoolId());
} catch (IOException e) {
// if it has not registered with the NN, throw an exception back.
throw new org.apache.hadoop.ipc.RetriableException(
"Datanode not registered. Try again later.");
}
if (isBlockTokenEnabled) {
Set<TokenIdentifier> tokenIds = UserGroupInformation.getCurrentUser()
.getTokenIdentifiers();

2
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNodeFaultInjector.java
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@ -49,4 +49,6 @@ public class DataNodeFaultInjector {
public boolean dropHeartbeatPacket() {
return false;
}
public void noRegistration() throws IOException { }
}

122
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiver.java
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@ -45,6 +45,7 @@ import java.net.SocketTimeoutException;
import java.nio.channels.ClosedChannelException;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.hadoop.fs.StorageType;
@ -85,6 +86,7 @@ import org.apache.hadoop.net.unix.DomainSocket;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.DataChecksum;
import org.apache.hadoop.util.StopWatch;
import com.google.common.base.Preconditions;
import com.google.protobuf.ByteString;
@ -296,6 +298,9 @@ class DataXceiver extends Receiver implements Runnable {
SlotId slotId, int maxVersion, boolean supportsReceiptVerification)
throws IOException {
updateCurrentThreadName("Passing file descriptors for block " + blk);
DataOutputStream out = getBufferedOutputStream();
checkAccess(out, true, blk, token,
Op.REQUEST_SHORT_CIRCUIT_FDS, BlockTokenSecretManager.AccessMode.READ);
BlockOpResponseProto.Builder bld = BlockOpResponseProto.newBuilder();
FileInputStream fis[] = null;
SlotId registeredSlotId = null;
@ -324,9 +329,6 @@ class DataXceiver extends Receiver implements Runnable {
} catch (ShortCircuitFdsUnsupportedException e) {
bld.setStatus(ERROR_UNSUPPORTED);
bld.setMessage(e.getMessage());
} catch (InvalidToken e) {
bld.setStatus(ERROR_ACCESS_TOKEN);
bld.setMessage(e.getMessage());
} catch (IOException e) {
bld.setStatus(ERROR);
bld.setMessage(e.getMessage());
@ -513,9 +515,9 @@ class DataXceiver extends Receiver implements Runnable {
final CachingStrategy cachingStrategy) throws IOException {
previousOpClientName = clientName;
long read = 0;
updateCurrentThreadName("Sending block " + block);
OutputStream baseStream = getOutputStream();
DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
baseStream, HdfsConstants.SMALL_BUFFER_SIZE));
DataOutputStream out = getBufferedOutputStream();
checkAccess(out, true, block, blockToken,
Op.READ_BLOCK, BlockTokenSecretManager.AccessMode.READ);
@ -531,7 +533,6 @@ class DataXceiver extends Receiver implements Runnable {
: dnR + " Served block " + block + " to " +
remoteAddress;
updateCurrentThreadName("Sending block " + block);
try {
try {
blockSender = new BlockSender(block, blockOffset, length,
@ -625,6 +626,10 @@ class DataXceiver extends Receiver implements Runnable {
final boolean isTransfer = stage == BlockConstructionStage.TRANSFER_RBW
|| stage == BlockConstructionStage.TRANSFER_FINALIZED;
long size = 0;
// reply to upstream datanode or client
final DataOutputStream replyOut = getBufferedOutputStream();
checkAccess(replyOut, isClient, block, blockToken,
Op.WRITE_BLOCK, BlockTokenSecretManager.AccessMode.WRITE);
// check single target for transfer-RBW/Finalized
if (isTransfer && targets.length > 0) {
throw new IOException(stage + " does not support multiple targets "
@ -655,14 +660,6 @@ class DataXceiver extends Receiver implements Runnable {
LOG.info("Receiving " + block + " src: " + remoteAddress + " dest: "
+ localAddress);
// reply to upstream datanode or client
final DataOutputStream replyOut = new DataOutputStream(
new BufferedOutputStream(
getOutputStream(),
HdfsConstants.SMALL_BUFFER_SIZE));
checkAccess(replyOut, isClient, block, blockToken,
Op.WRITE_BLOCK, BlockTokenSecretManager.AccessMode.WRITE);
DataOutputStream mirrorOut = null; // stream to next target
DataInputStream mirrorIn = null; // reply from next target
Socket mirrorSock = null; // socket to next target
@ -858,13 +855,13 @@ class DataXceiver extends Receiver implements Runnable {
final String clientName,
final DatanodeInfo[] targets,
final StorageType[] targetStorageTypes) throws IOException {
checkAccess(socketOut, true, blk, blockToken,
Op.TRANSFER_BLOCK, BlockTokenSecretManager.AccessMode.COPY);
previousOpClientName = clientName;
updateCurrentThreadName(Op.TRANSFER_BLOCK + " " + blk);
final DataOutputStream out = new DataOutputStream(
getOutputStream());
checkAccess(out, true, blk, blockToken,
Op.TRANSFER_BLOCK, BlockTokenSecretManager.AccessMode.COPY);
try {
datanode.transferReplicaForPipelineRecovery(blk, targets,
targetStorageTypes, clientName);
@ -918,6 +915,7 @@ class DataXceiver extends Receiver implements Runnable {
@Override
public void blockChecksum(final ExtendedBlock block,
final Token<BlockTokenIdentifier> blockToken) throws IOException {
updateCurrentThreadName("Getting checksum for block " + block);
final DataOutputStream out = new DataOutputStream(
getOutputStream());
checkAccess(out, true, block, blockToken,
@ -928,13 +926,11 @@ class DataXceiver extends Receiver implements Runnable {
long visibleLength = datanode.data.getReplicaVisibleLength(block);
boolean partialBlk = requestLength < visibleLength;
updateCurrentThreadName("Reading metadata for block " + block);
final LengthInputStream metadataIn = datanode.data
.getMetaDataInputStream(block);
final DataInputStream checksumIn = new DataInputStream(
new BufferedInputStream(metadataIn, HdfsConstants.IO_FILE_BUFFER_SIZE));
updateCurrentThreadName("Getting checksum for block " + block);
try {
//read metadata file
final BlockMetadataHeader header = BlockMetadataHeader
@ -982,21 +978,10 @@ class DataXceiver extends Receiver implements Runnable {
public void copyBlock(final ExtendedBlock block,
final Token<BlockTokenIdentifier> blockToken) throws IOException {
updateCurrentThreadName("Copying block " + block);
// Read in the header
if (datanode.isBlockTokenEnabled) {
try {
datanode.blockPoolTokenSecretManager.checkAccess(blockToken, null, block,
BlockTokenSecretManager.AccessMode.COPY);
} catch (InvalidToken e) {
LOG.warn("Invalid access token in request from " + remoteAddress
+ " for OP_COPY_BLOCK for block " + block + " : "
+ e.getLocalizedMessage());
sendResponse(ERROR_ACCESS_TOKEN, "Invalid access token");
return;
}
DataOutputStream reply = getBufferedOutputStream();
checkAccess(reply, true, block, blockToken,
Op.COPY_BLOCK, BlockTokenSecretManager.AccessMode.COPY);
}
if (datanode.data.getPinning(block)) {
String msg = "Not able to copy block " + block.getBlockId() + " " +
"to " + peer.getRemoteAddressString() + " because it's pinned ";
@ -1014,7 +999,6 @@ class DataXceiver extends Receiver implements Runnable {
}
BlockSender blockSender = null;
DataOutputStream reply = null;
boolean isOpSuccess = true;
try {
@ -1022,10 +1006,7 @@ class DataXceiver extends Receiver implements Runnable {
blockSender = new BlockSender(block, 0, -1, false, false, true, datanode,
null, CachingStrategy.newDropBehind());
// set up response stream
OutputStream baseStream = getOutputStream();
reply = new DataOutputStream(new BufferedOutputStream(
baseStream, HdfsConstants.SMALL_BUFFER_SIZE));
// send status first
writeSuccessWithChecksumInfo(blockSender, reply);
@ -1069,20 +1050,9 @@ class DataXceiver extends Receiver implements Runnable {
final String delHint,
final DatanodeInfo proxySource) throws IOException {
updateCurrentThreadName("Replacing block " + block + " from " + delHint);
/* read header */
if (datanode.isBlockTokenEnabled) {
try {
datanode.blockPoolTokenSecretManager.checkAccess(blockToken, null, block,
BlockTokenSecretManager.AccessMode.REPLACE);
} catch (InvalidToken e) {
LOG.warn("Invalid access token in request from " + remoteAddress
+ " for OP_REPLACE_BLOCK for block " + block + " : "
+ e.getLocalizedMessage());
sendResponse(ERROR_ACCESS_TOKEN, "Invalid access token");
return;
}
}
DataOutputStream replyOut = new DataOutputStream(getOutputStream());
checkAccess(replyOut, true, block, blockToken,
Op.REPLACE_BLOCK, BlockTokenSecretManager.AccessMode.REPLACE);
if (!dataXceiverServer.balanceThrottler.acquire()) { // not able to start
String msg = "Not able to receive block " + block.getBlockId() +
@ -1099,7 +1069,6 @@ class DataXceiver extends Receiver implements Runnable {
String errMsg = null;
BlockReceiver blockReceiver = null;
DataInputStream proxyReply = null;
DataOutputStream replyOut = new DataOutputStream(getOutputStream());
boolean IoeDuringCopyBlockOperation = false;
try {
// Move the block to different storage in the same datanode
@ -1211,6 +1180,16 @@ class DataXceiver extends Receiver implements Runnable {
datanode.metrics.addReplaceBlockOp(elapsed());
}
/**
* Separated for testing.
* @return
*/
DataOutputStream getBufferedOutputStream() {
return new DataOutputStream(
new BufferedOutputStream(getOutputStream(),
HdfsConstants.SMALL_BUFFER_SIZE));
}
private long elapsed() {
return monotonicNow() - opStartTime;
}
@ -1257,11 +1236,52 @@ class DataXceiver extends Receiver implements Runnable {
datanode.incrDatanodeNetworkErrors(remoteAddressWithoutPort);
}
/**
* Wait until the BP is registered, upto the configured amount of time.
* Throws an exception if times out, which should fail the client request.
* @param the requested block
*/
void checkAndWaitForBP(final ExtendedBlock block)
throws IOException {
String bpId = block.getBlockPoolId();
// The registration is only missing in relatively short time window.
// Optimistically perform this first.
try {
datanode.getDNRegistrationForBP(bpId);
return;
} catch (IOException ioe) {
// not registered
}
// retry
long bpReadyTimeout = dnConf.getBpReadyTimeout();
StopWatch sw = new StopWatch();
sw.start();
while (sw.now(TimeUnit.SECONDS) <= bpReadyTimeout) {
try {
datanode.getDNRegistrationForBP(bpId);
return;
} catch (IOException ioe) {
// not registered
}
// sleep before trying again
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
throw new IOException("Interrupted while serving request. Aborting.");
}
}
// failed to obtain registration.
throw new IOException("Not ready to serve the block pool, " + bpId + ".");
}
private void checkAccess(OutputStream out, final boolean reply,
final ExtendedBlock blk,
final Token<BlockTokenIdentifier> t,
final Op op,
final BlockTokenSecretManager.AccessMode mode) throws IOException {
checkAndWaitForBP(blk);
if (datanode.isBlockTokenEnabled) {
if (LOG.isDebugEnabled()) {
LOG.debug("Checking block access token for block '" + blk.getBlockId()

10
hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
View File

@ -2320,4 +2320,14 @@
<description>Whether pin blocks on favored DataNode.</description>
</property>
<property>
<name>dfs.datanode.bp-ready.timeout</name>
<value>20</value>
<description>
The maximum wait time for datanode to be ready before failing the
received request. Setting this to 0 fails requests right away if the
datanode is not yet registered with the namenode. This wait time
reduces initial request failures after datanode restart.
</description>
</property>
</configuration>

73
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/TestDatanodeRestart.java
View File

@ -37,6 +37,7 @@ import org.apache.hadoop.hdfs.MiniDFSCluster;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.datanode.DataNodeFaultInjector;
import org.apache.hadoop.hdfs.server.datanode.DataNodeTestUtils;
import org.apache.hadoop.hdfs.server.datanode.DatanodeUtil;
import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo;
@ -211,4 +212,76 @@ public class TestDatanodeRestart {
}
}
}
@Test
public void testWaitForRegistrationOnRestart() throws Exception {
Configuration conf = new HdfsConfiguration();
conf.setLong(DFSConfigKeys.DFS_DATANODE_BP_READY_TIMEOUT_KEY, 5);
conf.setInt(DFSConfigKeys.DFS_CLIENT_SOCKET_TIMEOUT_KEY, 5000);
// This makes the datanode appear registered to the NN, but it won't be
// able to get to the saved dn reg internally.
DataNodeFaultInjector dnFaultInjector = new DataNodeFaultInjector() {
@Override
public void noRegistration() throws IOException {
throw new IOException("no reg found for testing");
}
};
DataNodeFaultInjector oldDnInjector = DataNodeFaultInjector.get();
DataNodeFaultInjector.set(dnFaultInjector);
MiniDFSCluster cluster = null;
long start = 0;
Path file = new Path("/reg");
try {
int numDNs = 1;
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(numDNs).build();
cluster.waitActive();
start = System.currentTimeMillis();
FileSystem fileSys = cluster.getFileSystem();
try {
DFSTestUtil.createFile(fileSys, file, 10240L, (short)1, 0L);
// It is a bug if this does not fail.
throw new IOException("Did not fail!");
} catch (org.apache.hadoop.ipc.RemoteException e) {
long elapsed = System.currentTimeMillis() - start;
// timers have at-least semantics, so it should be at least 5 seconds.
if (elapsed < 5000 || elapsed > 10000) {
throw new IOException(elapsed + " seconds passed.", e);
}
}
DataNodeFaultInjector.set(oldDnInjector);
// this should succeed now.
DFSTestUtil.createFile(fileSys, file, 10240L, (short)1, 0L);
// turn it back to under-construction, so that the client calls
// getReplicaVisibleLength() rpc method against the datanode.
fileSys.append(file);
// back to simulating unregistered node.
DataNodeFaultInjector.set(dnFaultInjector);
byte[] buffer = new byte[8];
start = System.currentTimeMillis();
try {
fileSys.open(file).read(0L, buffer, 0, 1);
throw new IOException("Did not fail!");
} catch (IOException e) {
long elapsed = System.currentTimeMillis() - start;
if (e.getMessage().contains("readBlockLength")) {
throw new IOException("Failed, but with unexpected exception:", e);
}
// timers have at-least semantics, so it should be at least 5 seconds.
if (elapsed < 5000 || elapsed > 10000) {
throw new IOException(elapsed + " seconds passed.", e);
}
}
DataNodeFaultInjector.set(oldDnInjector);
fileSys.open(file).read(0L, buffer, 0, 1);
} finally {
DataNodeFaultInjector.set(oldDnInjector);
if (cluster != null) {
cluster.shutdown();
}
}
}
}