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HDFS-6899. Allow changing MiniDFSCluster volumes per DN and capacity per volume. (Arpit Agarwal)

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git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1619970 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Arpit Agarwal 2014-08-23 06:01:17 +00:00
parent a83d055f25
commit e871955765
8 changed files with 171 additions and 37 deletions
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3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
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@ -507,6 +507,9 @@ Release 2.6.0 - UNRELEASED
HDFS-6758. block writer should pass the expected block size to
DataXceiverServer. (Arpit Agarwal)
HDFS-6899. Allow changing MiniDFSCluster volumes per DN and capacity
per volume. (Arpit Agarwal)
OPTIMIZATIONS
HDFS-6690. Deduplicate xattr names in memory. (wang)

41
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeImpl.java
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@ -29,6 +29,7 @@
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.DF;
@ -50,7 +51,8 @@
* It uses the {@link FsDatasetImpl} object for synchronization.
*/
@InterfaceAudience.Private
class FsVolumeImpl implements FsVolumeSpi {
@VisibleForTesting
public class FsVolumeImpl implements FsVolumeSpi {
private final FsDatasetImpl dataset;
private final String storageID;
private final StorageType storageType;
@ -59,6 +61,12 @@ class FsVolumeImpl implements FsVolumeSpi {
private final File currentDir; // <StorageDirectory>/current
private final DF usage;
private final long reserved;
// Capacity configured. This is useful when we want to
// limit the visible capacity for tests. If negative, then we just
// query from the filesystem.
protected long configuredCapacity;
/**
* Per-volume worker pool that processes new blocks to cache.
* The maximum number of workers per volume is bounded (configurable via
@ -78,20 +86,26 @@ class FsVolumeImpl implements FsVolumeSpi {
File parent = currentDir.getParentFile();
this.usage = new DF(parent, conf);
this.storageType = storageType;
this.configuredCapacity = -1;
cacheExecutor = initializeCacheExecutor(parent);
}
protected ThreadPoolExecutor initializeCacheExecutor(File parent) {
final int maxNumThreads = dataset.datanode.getConf().getInt(
DFSConfigKeys.DFS_DATANODE_FSDATASETCACHE_MAX_THREADS_PER_VOLUME_KEY,
DFSConfigKeys.DFS_DATANODE_FSDATASETCACHE_MAX_THREADS_PER_VOLUME_DEFAULT
);
DFSConfigKeys.DFS_DATANODE_FSDATASETCACHE_MAX_THREADS_PER_VOLUME_DEFAULT);
ThreadFactory workerFactory = new ThreadFactoryBuilder()
.setDaemon(true)
.setNameFormat("FsVolumeImplWorker-" + parent.toString() + "-%d")
.build();
cacheExecutor = new ThreadPoolExecutor(
ThreadPoolExecutor executor = new ThreadPoolExecutor(
1, maxNumThreads,
60, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(),
workerFactory);
cacheExecutor.allowCoreThreadTimeOut(true);
executor.allowCoreThreadTimeOut(true);
return executor;
}
File getCurrentDir() {
@ -130,11 +144,26 @@ long getBlockPoolUsed(String bpid) throws IOException {
* reserved capacity.
* @return the unreserved number of bytes left in this filesystem. May be zero.
*/
long getCapacity() {
@VisibleForTesting
public long getCapacity() {
if (configuredCapacity < 0) {
long remaining = usage.getCapacity() - reserved;
return remaining > 0 ? remaining : 0;
}
return configuredCapacity;
}
/**
* This function MUST NOT be used outside of tests.
*
* @param capacity
*/
@VisibleForTesting
public void setCapacityForTesting(long capacity) {
this.configuredCapacity = capacity;
}
@Override
public long getAvailable() throws IOException {
long remaining = getCapacity()-getDfsUsed();

113
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java
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@ -55,7 +55,6 @@
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.channels.FileChannel;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
@ -91,7 +90,9 @@
import org.apache.hadoop.hdfs.server.datanode.SecureDataNodeStarter.SecureResources;
import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetUtil;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.NameNode;
import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
@ -131,11 +132,15 @@ public class MiniDFSCluster {
public static final String DFS_NAMENODE_SAFEMODE_EXTENSION_TESTING_KEY
= DFS_NAMENODE_SAFEMODE_EXTENSION_KEY + ".testing";
// Changing this value may break some tests that assume it is 2.
public static final int DIRS_PER_DATANODE = 2;
// Changing this default may break some tests that assume it is 2.
private static final int DEFAULT_STORAGES_PER_DATANODE = 2;
static { DefaultMetricsSystem.setMiniClusterMode(true); }
public int getStoragesPerDatanode() {
return storagesPerDatanode;
}
/**
* Class to construct instances of MiniDFSClusters with specific options.
*/
@ -145,6 +150,8 @@ public static class Builder {
private final Configuration conf;
private int numDataNodes = 1;
private StorageType[][] storageTypes = null;
private StorageType[] storageTypes1D = null;
private int storagesPerDatanode = DEFAULT_STORAGES_PER_DATANODE;
private boolean format = true;
private boolean manageNameDfsDirs = true;
private boolean manageNameDfsSharedDirs = true;
@ -155,6 +162,8 @@ public static class Builder {
private String[] racks = null;
private String [] hosts = null;
private long [] simulatedCapacities = null;
private long [][] storageCapacities = null;
private long [] storageCapacities1D = null;
private String clusterId = null;
private boolean waitSafeMode = true;
private boolean setupHostsFile = false;
@ -192,17 +201,21 @@ public Builder numDataNodes(int val) {
return this;
}
/**
* Default: DEFAULT_STORAGES_PER_DATANODE
*/
public Builder storagesPerDatanode(int numStorages) {
this.storagesPerDatanode = numStorages;
return this;
}
/**
* Set the same storage type configuration for each datanode.
* If storageTypes is uninitialized or passed null then
* StorageType.DEFAULT is used.
*/
public Builder storageTypes(StorageType[] types) {
assert types.length == DIRS_PER_DATANODE;
this.storageTypes = new StorageType[numDataNodes][types.length];
for (int i = 0; i < numDataNodes; ++i) {
this.storageTypes[i] = types;
}
this.storageTypes1D = types;
return this;
}
@ -216,6 +229,26 @@ public Builder storageTypes(StorageType[][] types) {
return this;
}
/**
* Set the same storage capacity configuration for each datanode.
* If storageTypes is uninitialized or passed null then
* StorageType.DEFAULT is used.
*/
public Builder storageCapacities(long[] capacities) {
this.storageCapacities1D = capacities;
return this;
}
/**
* Set custom storage capacity configuration for each datanode.
* If storageCapacities is uninitialized or passed null then
* capacity is limited by available disk space.
*/
public Builder storageCapacities(long[][] capacities) {
this.storageCapacities = capacities;
return this;
}
/**
* Default: true
*/
@ -289,6 +322,11 @@ public Builder hosts(String[] val) {
}
/**
* Use SimulatedFSDataset and limit the capacity of each DN per
* the values passed in val.
*
* For limiting the capacity of volumes with real storage, see
* {@link FsVolumeImpl#setCapacityForTesting}
* Default: null
*/
public Builder simulatedCapacities(long[] val) {
@ -391,6 +429,27 @@ protected MiniDFSCluster(Builder builder) throws IOException {
LOG.info("starting cluster: numNameNodes=" + numNameNodes
+ ", numDataNodes=" + builder.numDataNodes);
nameNodes = new NameNodeInfo[numNameNodes];
this.storagesPerDatanode = builder.storagesPerDatanode;
// Duplicate the storageType setting for each DN.
if (builder.storageTypes == null && builder.storageTypes1D != null) {
assert builder.storageTypes1D.length == storagesPerDatanode;
builder.storageTypes = new StorageType[builder.numDataNodes][storagesPerDatanode];
for (int i = 0; i < builder.numDataNodes; ++i) {
builder.storageTypes[i] = builder.storageTypes1D;
}
}
// Duplicate the storageCapacity setting for each DN.
if (builder.storageCapacities == null && builder.storageCapacities1D != null) {
assert builder.storageCapacities1D.length == storagesPerDatanode;
builder.storageCapacities = new long[builder.numDataNodes][storagesPerDatanode];
for (int i = 0; i < builder.numDataNodes; ++i) {
builder.storageCapacities[i] = builder.storageCapacities1D;
}
}
initMiniDFSCluster(builder.conf,
builder.numDataNodes,
@ -404,6 +463,7 @@ protected MiniDFSCluster(Builder builder) throws IOException {
builder.dnOption,
builder.racks,
builder.hosts,
builder.storageCapacities,
builder.simulatedCapacities,
builder.clusterId,
builder.waitSafeMode,
@ -446,6 +506,7 @@ public void setDnArgs(String ... args) {
private boolean waitSafeMode = true;
private boolean federation;
private boolean checkExitOnShutdown = true;
protected final int storagesPerDatanode;
/**
* A unique instance identifier for the cluster. This
@ -484,6 +545,7 @@ public void setStartOpt(StartupOption startOpt) {
*/
public MiniDFSCluster() {
nameNodes = new NameNodeInfo[0]; // No namenode in the cluster
storagesPerDatanode = DEFAULT_STORAGES_PER_DATANODE;
synchronized (MiniDFSCluster.class) {
instanceId = instanceCount++;
}
@ -660,10 +722,11 @@ public MiniDFSCluster(int nameNodePort,
String[] racks, String hosts[],
long[] simulatedCapacities) throws IOException {
this.nameNodes = new NameNodeInfo[1]; // Single namenode in the cluster
this.storagesPerDatanode = DEFAULT_STORAGES_PER_DATANODE;
initMiniDFSCluster(conf, numDataNodes, null, format,
manageNameDfsDirs, true, manageDataDfsDirs, manageDataDfsDirs,
operation, null, racks, hosts,
simulatedCapacities, null, true, false,
null, simulatedCapacities, null, true, false,
MiniDFSNNTopology.simpleSingleNN(nameNodePort, 0), true, false, false, null);
}
@ -673,7 +736,8 @@ private void initMiniDFSCluster(
boolean manageNameDfsSharedDirs, boolean enableManagedDfsDirsRedundancy,
boolean manageDataDfsDirs, StartupOption startOpt,
StartupOption dnStartOpt, String[] racks,
String[] hosts, long[] simulatedCapacities, String clusterId,
String[] hosts,
long[][] storageCapacities, long[] simulatedCapacities, String clusterId,
boolean waitSafeMode, boolean setupHostsFile,
MiniDFSNNTopology nnTopology, boolean checkExitOnShutdown,
boolean checkDataNodeAddrConfig,
@ -744,7 +808,7 @@ private void initMiniDFSCluster(
// Start the DataNodes
startDataNodes(conf, numDataNodes, storageTypes, manageDataDfsDirs,
dnStartOpt != null ? dnStartOpt : startOpt,
racks, hosts, simulatedCapacities, setupHostsFile,
racks, hosts, storageCapacities, simulatedCapacities, setupHostsFile,
checkDataNodeAddrConfig, checkDataNodeHostConfig, dnConfOverlays);
waitClusterUp();
//make sure ProxyUsers uses the latest conf
@ -1119,8 +1183,8 @@ public void waitClusterUp() throws IOException {
String makeDataNodeDirs(int dnIndex, StorageType[] storageTypes) throws IOException {
StringBuilder sb = new StringBuilder();
assert storageTypes == null || storageTypes.length == DIRS_PER_DATANODE;
for (int j = 0; j < DIRS_PER_DATANODE; ++j) {
assert storageTypes == null || storageTypes.length == storagesPerDatanode;
for (int j = 0; j < storagesPerDatanode; ++j) {
File dir = getInstanceStorageDir(dnIndex, j);
dir.mkdirs();
if (!dir.isDirectory()) {
@ -1196,7 +1260,7 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
long[] simulatedCapacities,
boolean setupHostsFile) throws IOException {
startDataNodes(conf, numDataNodes, null, manageDfsDirs, operation, racks, hosts,
simulatedCapacities, setupHostsFile, false, false, null);
null, simulatedCapacities, setupHostsFile, false, false, null);
}
public synchronized void startDataNodes(Configuration conf, int numDataNodes,
@ -1206,7 +1270,7 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
boolean setupHostsFile,
boolean checkDataNodeAddrConfig) throws IOException {
startDataNodes(conf, numDataNodes, null, manageDfsDirs, operation, racks, hosts,
simulatedCapacities, setupHostsFile, checkDataNodeAddrConfig, false, null);
null, simulatedCapacities, setupHostsFile, checkDataNodeAddrConfig, false, null);
}
/**
@ -1240,12 +1304,15 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
public synchronized void startDataNodes(Configuration conf, int numDataNodes,
StorageType[][] storageTypes, boolean manageDfsDirs, StartupOption operation,
String[] racks, String[] hosts,
long[][] storageCapacities,
long[] simulatedCapacities,
boolean setupHostsFile,
boolean checkDataNodeAddrConfig,
boolean checkDataNodeHostConfig,
Configuration[] dnConfOverlays) throws IOException {
assert storageCapacities == null || simulatedCapacities == null;
assert storageTypes == null || storageTypes.length == numDataNodes;
assert storageCapacities == null || storageCapacities.length == numDataNodes;
if (operation == StartupOption.RECOVER) {
return;
@ -1298,7 +1365,7 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
operation != StartupOption.ROLLBACK) ?
null : new String[] {operation.getName()};
DataNode[] dns = new DataNode[numDataNodes];
for (int i = curDatanodesNum; i < curDatanodesNum+numDataNodes; i++) {
Configuration dnConf = new HdfsConfiguration(conf);
if (dnConfOverlays != null) {
@ -1389,10 +1456,24 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
dn.runDatanodeDaemon();
dataNodes.add(new DataNodeProperties(dn, newconf, dnArgs,
secureResources, dn.getIpcPort()));
dns[i - curDatanodesNum] = dn;
}
curDatanodesNum += numDataNodes;
this.numDataNodes += numDataNodes;
waitActive();
if (storageCapacities != null) {
for (int i = curDatanodesNum; i < curDatanodesNum+numDataNodes; ++i) {
List<? extends FsVolumeSpi> volumes = dns[i].getFSDataset().getVolumes();
assert storageCapacities[i].length == storagesPerDatanode;
assert volumes.size() == storagesPerDatanode;
for (int j = 0; j < volumes.size(); ++j) {
FsVolumeImpl volume = (FsVolumeImpl) volumes.get(j);
volume.setCapacityForTesting(storageCapacities[i][j]);
}
}
}
}

26
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSClusterWithNodeGroup.java
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@ -22,6 +22,7 @@
import java.io.File;
import java.io.IOException;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
@ -31,6 +32,8 @@
import org.apache.hadoop.hdfs.server.datanode.SecureDataNodeStarter;
import org.apache.hadoop.hdfs.server.datanode.SimulatedFSDataset;
import org.apache.hadoop.hdfs.server.datanode.SecureDataNodeStarter.SecureResources;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsVolumeImpl;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.net.StaticMapping;
import org.apache.hadoop.security.UserGroupInformation;
@ -52,11 +55,15 @@ public static void setNodeGroups (String[] nodeGroups) {
public synchronized void startDataNodes(Configuration conf, int numDataNodes,
StorageType[][] storageTypes, boolean manageDfsDirs, StartupOption operation,
String[] racks, String[] nodeGroups, String[] hosts,
long[][] storageCapacities,
long[] simulatedCapacities,
boolean setupHostsFile,
boolean checkDataNodeAddrConfig,
boolean checkDataNodeHostConfig) throws IOException {
assert storageCapacities == null || simulatedCapacities == null;
assert storageTypes == null || storageTypes.length == numDataNodes;
assert storageCapacities == null || storageCapacities.length == numDataNodes;
if (operation == StartupOption.RECOVER) {
return;
@ -109,6 +116,7 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
operation != StartupOption.ROLLBACK) ?
null : new String[] {operation.getName()};
DataNode[] dns = new DataNode[numDataNodes];
for (int i = curDatanodesNum; i < curDatanodesNum+numDataNodes; i++) {
Configuration dnConf = new HdfsConfiguration(conf);
// Set up datanode address
@ -181,10 +189,23 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
}
dn.runDatanodeDaemon();
dataNodes.add(new DataNodeProperties(dn, newconf, dnArgs, secureResources, dn.getIpcPort()));
dns[i - curDatanodesNum] = dn;
}
curDatanodesNum += numDataNodes;
this.numDataNodes += numDataNodes;
waitActive();
if (storageCapacities != null) {
for (int i = curDatanodesNum; i < curDatanodesNum+numDataNodes; ++i) {
List<? extends FsVolumeSpi> volumes = dns[i].getFSDataset().getVolumes();
assert volumes.size() == storagesPerDatanode;
for (int j = 0; j < volumes.size(); ++j) {
FsVolumeImpl volume = (FsVolumeImpl) volumes.get(j);
volume.setCapacityForTesting(storageCapacities[i][j]);
}
}
}
}
public synchronized void startDataNodes(Configuration conf, int numDataNodes,
@ -193,7 +214,7 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
long[] simulatedCapacities,
boolean setupHostsFile) throws IOException {
startDataNodes(conf, numDataNodes, null, manageDfsDirs, operation, racks, nodeGroups,
hosts, simulatedCapacities, setupHostsFile, false, false);
hosts, null, simulatedCapacities, setupHostsFile, false, false);
}
public void startDataNodes(Configuration conf, int numDataNodes,
@ -209,13 +230,14 @@ public void startDataNodes(Configuration conf, int numDataNodes,
public synchronized void startDataNodes(Configuration conf, int numDataNodes,
StorageType[][] storageTypes, boolean manageDfsDirs, StartupOption operation,
String[] racks, String[] hosts,
long[][] storageCapacities,
long[] simulatedCapacities,
boolean setupHostsFile,
boolean checkDataNodeAddrConfig,
boolean checkDataNodeHostConfig,
Configuration[] dnConfOverlays) throws IOException {
startDataNodes(conf, numDataNodes, storageTypes, manageDfsDirs, operation, racks,
NODE_GROUPS, hosts, simulatedCapacities, setupHostsFile,
NODE_GROUPS, hosts, storageCapacities, simulatedCapacities, setupHostsFile,
checkDataNodeAddrConfig, checkDataNodeHostConfig);
}

2
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java
View File

@ -213,7 +213,7 @@ public void testInitializeReplQueuesEarly() throws Exception {
@Override
public Boolean get() {
return getLongCounter("StorageBlockReportOps", getMetrics(NN_METRICS)) ==
MiniDFSCluster.DIRS_PER_DATANODE;
cluster.getStoragesPerDatanode();
}
}, 10, 10000);

5
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestBlockHasMultipleReplicasOnSameDN.java
View File

@ -18,7 +18,6 @@
package org.apache.hadoop.hdfs.server.datanode;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.ArrayList;
@ -106,7 +105,7 @@ public void testBlockHasMultipleReplicasOnSameDN() throws IOException {
DataNode dn = cluster.getDataNodes().get(0);
DatanodeRegistration dnReg = dn.getDNRegistrationForBP(bpid);
StorageBlockReport reports[] =
new StorageBlockReport[MiniDFSCluster.DIRS_PER_DATANODE];
new StorageBlockReport[cluster.getStoragesPerDatanode()];
ArrayList<Block> blocks = new ArrayList<Block>();
@ -114,7 +113,7 @@ public void testBlockHasMultipleReplicasOnSameDN() throws IOException {
blocks.add(locatedBlock.getBlock().getLocalBlock());
}
for (int i = 0; i < MiniDFSCluster.DIRS_PER_DATANODE; ++i) {
for (int i = 0; i < cluster.getStoragesPerDatanode(); ++i) {
BlockListAsLongs bll = new BlockListAsLongs(blocks, null);
FsVolumeSpi v = dn.getFSDataset().getVolumes().get(i);
DatanodeStorage dns = new DatanodeStorage(v.getStorageID());

6
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDnRespectsBlockReportSplitThreshold.java
View File

@ -130,7 +130,7 @@ public void testAlwaysSplit() throws IOException, InterruptedException {
ArgumentCaptor<StorageBlockReport[]> captor =
ArgumentCaptor.forClass(StorageBlockReport[].class);
Mockito.verify(nnSpy, times(MiniDFSCluster.DIRS_PER_DATANODE)).blockReport(
Mockito.verify(nnSpy, times(cluster.getStoragesPerDatanode())).blockReport(
any(DatanodeRegistration.class),
anyString(),
captor.capture());
@ -167,7 +167,7 @@ public void testCornerCaseUnderThreshold() throws IOException, InterruptedExcept
anyString(),
captor.capture());
verifyCapturedArguments(captor, MiniDFSCluster.DIRS_PER_DATANODE, BLOCKS_IN_FILE);
verifyCapturedArguments(captor, cluster.getStoragesPerDatanode(), BLOCKS_IN_FILE);
}
/**
@ -194,7 +194,7 @@ public void testCornerCaseAtThreshold() throws IOException, InterruptedException
ArgumentCaptor<StorageBlockReport[]> captor =
ArgumentCaptor.forClass(StorageBlockReport[].class);
Mockito.verify(nnSpy, times(MiniDFSCluster.DIRS_PER_DATANODE)).blockReport(
Mockito.verify(nnSpy, times(cluster.getStoragesPerDatanode())).blockReport(
any(DatanodeRegistration.class),
anyString(),
captor.capture());

2
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java
View File

@ -443,7 +443,7 @@ public void testSyncAndBlockReportMetric() throws Exception {
assertCounter("SyncsNumOps", 1L, rb);
// Each datanode reports in when the cluster comes up
assertCounter("BlockReportNumOps",
(long)DATANODE_COUNT*MiniDFSCluster.DIRS_PER_DATANODE, rb);
(long)DATANODE_COUNT * cluster.getStoragesPerDatanode(), rb);
// Sleep for an interval+slop to let the percentiles rollover
Thread.sleep((PERCENTILES_INTERVAL+1)*1000);