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HDFS-9801. ReconfigurableBase should update the cached configuration. (Arpit Agarwal)

This commit is contained in:
Arpit Agarwal 2016-02-12 12:41:04 -08:00
parent 4d7da8907f
commit 8c1cf718aa
8 changed files with 292 additions and 101 deletions
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8
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Reconfigurable.java
View File

@ -36,7 +36,7 @@ public interface Reconfigurable extends Configurable {
* If the property cannot be changed, throw a
* {@link ReconfigurationException}.
*/
public String reconfigureProperty(String property, String newVal)
void reconfigureProperty(String property, String newVal)
throws ReconfigurationException;
/**
@ -46,12 +46,10 @@ public String reconfigureProperty(String property, String newVal)
* then changeConf should not throw an exception when changing
* this property.
*/
public boolean isPropertyReconfigurable(String property);
boolean isPropertyReconfigurable(String property);
/**
* Return all the properties that can be changed at run time.
*/
public Collection<String> getReconfigurableProperties();
Collection<String> getReconfigurableProperties();
}

47
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurableBase.java
View File

@ -112,14 +112,14 @@ private static class ReconfigurationThread extends Thread {
// See {@link ReconfigurationServlet#applyChanges}
public void run() {
LOG.info("Starting reconfiguration task.");
Configuration oldConf = this.parent.getConf();
Configuration newConf = this.parent.getNewConf();
Collection<PropertyChange> changes =
this.parent.getChangedProperties(newConf, oldConf);
final Configuration oldConf = parent.getConf();
final Configuration newConf = parent.getNewConf();
final Collection<PropertyChange> changes =
parent.getChangedProperties(newConf, oldConf);
Map<PropertyChange, Optional<String>> results = Maps.newHashMap();
for (PropertyChange change : changes) {
String errorMessage = null;
if (!this.parent.isPropertyReconfigurable(change.prop)) {
if (!parent.isPropertyReconfigurable(change.prop)) {
LOG.info(String.format(
"Property %s is not configurable: old value: %s, new value: %s",
change.prop, change.oldVal, change.newVal));
@ -130,17 +130,23 @@ public void run() {
+ "\" to \"" + ((change.newVal == null) ? "<default>" : change.newVal)
+ "\".");
try {
this.parent.reconfigurePropertyImpl(change.prop, change.newVal);
String effectiveValue =
parent.reconfigurePropertyImpl(change.prop, change.newVal);
if (change.newVal != null) {
oldConf.set(change.prop, effectiveValue);
} else {
oldConf.unset(change.prop);
}
} catch (ReconfigurationException e) {
errorMessage = e.getCause().getMessage();
}
results.put(change, Optional.fromNullable(errorMessage));
}
synchronized (this.parent.reconfigLock) {
this.parent.endTime = Time.now();
this.parent.status = Collections.unmodifiableMap(results);
this.parent.reconfigThread = null;
synchronized (parent.reconfigLock) {
parent.endTime = Time.now();
parent.status = Collections.unmodifiableMap(results);
parent.reconfigThread = null;
}
}
}
@ -203,21 +209,19 @@ public void shutdownReconfigurationTask() {
* reconfigureProperty.
*/
@Override
public final String reconfigureProperty(String property, String newVal)
public final void reconfigureProperty(String property, String newVal)
throws ReconfigurationException {
if (isPropertyReconfigurable(property)) {
LOG.info("changing property " + property + " to " + newVal);
String oldVal;
synchronized(getConf()) {
oldVal = getConf().get(property);
reconfigurePropertyImpl(property, newVal);
getConf().get(property);
String effectiveValue = reconfigurePropertyImpl(property, newVal);
if (newVal != null) {
getConf().set(property, newVal);
getConf().set(property, effectiveValue);
} else {
getConf().unset(property);
}
}
return oldVal;
} else {
throw new ReconfigurationException(property, newVal,
getConf().get(property));
@ -251,8 +255,15 @@ public boolean isPropertyReconfigurable(String property) {
* that is being changed. If this object owns other Reconfigurable objects
* reconfigureProperty should be called recursively to make sure that
* to make sure that the configuration of these objects is updated.
*
* @param property Name of the property that is being reconfigured.
* @param newVal Proposed new value of the property.
* @return Effective new value of the property. This may be different from
* newVal.
*
* @throws ReconfigurationException if there was an error applying newVal.
*/
protected abstract void reconfigurePropertyImpl(String property, String newVal)
throws ReconfigurationException;
protected abstract String reconfigurePropertyImpl(
String property, String newVal) throws ReconfigurationException;
}

143
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestReconfiguration.java
View File

@ -19,6 +19,7 @@
package org.apache.hadoop.conf;
import com.google.common.base.Optional;
import com.google.common.base.Supplier;
import com.google.common.collect.Lists;
import org.apache.hadoop.test.GenericTestUtils;
import org.apache.hadoop.util.Time;
@ -27,13 +28,13 @@
import org.junit.Before;
import static org.hamcrest.CoreMatchers.containsString;
import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.junit.Assert.*;
import static org.junit.Assert.assertEquals;
import static org.mockito.Matchers.any;
import static org.mockito.Matchers.anyString;
import static org.mockito.Matchers.eq;
import static org.mockito.Mockito.doNothing;
import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.doThrow;
import static org.mockito.Mockito.spy;
@ -44,6 +45,7 @@
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeoutException;
public class TestReconfiguration {
private Configuration conf1;
@ -129,9 +131,10 @@ public Collection<String> getReconfigurableProperties() {
}
@Override
public synchronized void reconfigurePropertyImpl(
public synchronized String reconfigurePropertyImpl(
String property, String newVal) throws ReconfigurationException {
// do nothing
return newVal;
}
/**
@ -354,13 +357,14 @@ public Collection<String> getReconfigurableProperties() {
}
@Override
public synchronized void reconfigurePropertyImpl(String property,
public synchronized String reconfigurePropertyImpl(String property,
String newVal) throws ReconfigurationException {
try {
latch.await();
} catch (InterruptedException e) {
// Ignore
}
return newVal;
}
}
@ -395,9 +399,9 @@ public void testAsyncReconfigure()
doReturn(false).when(dummy).isPropertyReconfigurable(eq("name2"));
doReturn(true).when(dummy).isPropertyReconfigurable(eq("name3"));
doNothing().when(dummy)
doReturn("dummy").when(dummy)
.reconfigurePropertyImpl(eq("name1"), anyString());
doNothing().when(dummy)
doReturn("dummy").when(dummy)
.reconfigurePropertyImpl(eq("name2"), anyString());
doThrow(new ReconfigurationException("NAME3", "NEW3", "OLD3",
new IOException("io exception")))
@ -474,4 +478,131 @@ public void testStartReconfigurationFailureDueToExistingRunningTask()
GenericTestUtils.assertExceptionContains("The server is stopped", e);
}
}
}
/**
* Ensure that {@link ReconfigurableBase#reconfigureProperty} updates the
* parent's cached configuration on success.
* @throws IOException
*/
@Test (timeout=300000)
public void testConfIsUpdatedOnSuccess() throws ReconfigurationException {
final String property = "FOO";
final String value1 = "value1";
final String value2 = "value2";
final Configuration conf = new Configuration();
conf.set(property, value1);
final Configuration newConf = new Configuration();
newConf.set(property, value2);
final ReconfigurableBase reconfigurable = makeReconfigurable(
conf, newConf, Arrays.asList(property));
reconfigurable.reconfigureProperty(property, value2);
assertThat(reconfigurable.getConf().get(property), is(value2));
}
/**
* Ensure that {@link ReconfigurableBase#startReconfigurationTask} updates
* its parent's cached configuration on success.
* @throws IOException
*/
@Test (timeout=300000)
public void testConfIsUpdatedOnSuccessAsync() throws ReconfigurationException,
TimeoutException, InterruptedException, IOException {
final String property = "FOO";
final String value1 = "value1";
final String value2 = "value2";
final Configuration conf = new Configuration();
conf.set(property, value1);
final Configuration newConf = new Configuration();
newConf.set(property, value2);
final ReconfigurableBase reconfigurable = makeReconfigurable(
conf, newConf, Arrays.asList(property));
// Kick off a reconfiguration task and wait until it completes.
reconfigurable.startReconfigurationTask();
GenericTestUtils.waitFor(new Supplier<Boolean>() {
@Override
public Boolean get() {
return reconfigurable.getReconfigurationTaskStatus().stopped();
}
}, 100, 60000);
assertThat(reconfigurable.getConf().get(property), is(value2));
}
/**
* Ensure that {@link ReconfigurableBase#reconfigureProperty} unsets the
* property in its parent's configuration when the new value is null.
* @throws IOException
*/
@Test (timeout=300000)
public void testConfIsUnset() throws ReconfigurationException {
final String property = "FOO";
final String value1 = "value1";
final Configuration conf = new Configuration();
conf.set(property, value1);
final Configuration newConf = new Configuration();
final ReconfigurableBase reconfigurable = makeReconfigurable(
conf, newConf, Arrays.asList(property));
reconfigurable.reconfigureProperty(property, null);
assertNull(reconfigurable.getConf().get(property));
}
/**
* Ensure that {@link ReconfigurableBase#startReconfigurationTask} unsets the
* property in its parent's configuration when the new value is null.
* @throws IOException
*/
@Test (timeout=300000)
public void testConfIsUnsetAsync() throws ReconfigurationException,
IOException, TimeoutException, InterruptedException {
final String property = "FOO";
final String value1 = "value1";
final Configuration conf = new Configuration();
conf.set(property, value1);
final Configuration newConf = new Configuration();
final ReconfigurableBase reconfigurable = makeReconfigurable(
conf, newConf, Arrays.asList(property));
// Kick off a reconfiguration task and wait until it completes.
reconfigurable.startReconfigurationTask();
GenericTestUtils.waitFor(new Supplier<Boolean>() {
@Override
public Boolean get() {
return reconfigurable.getReconfigurationTaskStatus().stopped();
}
}, 100, 60000);
assertNull(reconfigurable.getConf().get(property));
}
private ReconfigurableBase makeReconfigurable(
final Configuration oldConf, final Configuration newConf,
final Collection<String> reconfigurableProperties) {
return new ReconfigurableBase(oldConf) {
@Override
protected Configuration getNewConf() {
return newConf;
}
@Override
public Collection<String> getReconfigurableProperties() {
return reconfigurableProperties;
}
@Override
protected String reconfigurePropertyImpl(
String property, String newVal) throws ReconfigurationException {
return newVal;
}
};
}
}

3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
View File

@ -1757,6 +1757,9 @@ Release 2.8.0 - UNRELEASED
HDFS-9790. HDFS Balancer should exit with a proper message if upgrade is
not finalized. (Xiaobing Zhou via Arpit Agarwal)
HDFS-9801. ReconfigurableBase should update the cached configuration.
(Arpit Agarwal)
Release 2.7.3 - UNRELEASED
INCOMPATIBLE CHANGES

116
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
View File

@ -504,70 +504,80 @@ protected Configuration getNewConf() {
return new HdfsConfiguration();
}
/**
* {@inheritdoc}.
*/
@Override
public void reconfigurePropertyImpl(String property, String newVal)
public String reconfigurePropertyImpl(String property, String newVal)
throws ReconfigurationException {
if (property.equals(DFS_DATANODE_DATA_DIR_KEY)) {
IOException rootException = null;
try {
LOG.info("Reconfiguring " + property + " to " + newVal);
this.refreshVolumes(newVal);
} catch (IOException e) {
rootException = e;
} finally {
// Send a full block report to let NN acknowledge the volume changes.
switch (property) {
case DFS_DATANODE_DATA_DIR_KEY: {
IOException rootException = null;
try {
triggerBlockReport(
new BlockReportOptions.Factory().setIncremental(false).build());
LOG.info("Reconfiguring " + property + " to " + newVal);
this.refreshVolumes(newVal);
return conf.get(DFS_DATANODE_DATA_DIR_KEY);
} catch (IOException e) {
LOG.warn("Exception while sending the block report after refreshing"
+ " volumes " + property + " to " + newVal, e);
if (rootException == null) {
rootException = e;
rootException = e;
} finally {
// Send a full block report to let NN acknowledge the volume changes.
try {
triggerBlockReport(
new BlockReportOptions.Factory().setIncremental(false).build());
} catch (IOException e) {
LOG.warn("Exception while sending the block report after refreshing"
+ " volumes " + property + " to " + newVal, e);
if (rootException == null) {
rootException = e;
}
} finally {
if (rootException != null) {
throw new ReconfigurationException(property, newVal,
getConf().get(property), rootException);
}
}
}
break;
}
case DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_KEY: {
ReconfigurationException rootException = null;
try {
LOG.info("Reconfiguring " + property + " to " + newVal);
int movers;
if (newVal == null) {
// set to default
movers = DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_DEFAULT;
} else {
movers = Integer.parseInt(newVal);
if (movers <= 0) {
rootException = new ReconfigurationException(
property,
newVal,
getConf().get(property),
new IllegalArgumentException(
"balancer max concurrent movers must be larger than 0"));
}
}
xserver.updateBalancerMaxConcurrentMovers(movers);
return Integer.toString(movers);
} catch (NumberFormatException nfe) {
rootException = new ReconfigurationException(
property, newVal, getConf().get(property), nfe);
} finally {
if (rootException != null) {
throw new ReconfigurationException(property, newVal,
getConf().get(property), rootException);
LOG.warn(String.format(
"Exception in updating balancer max concurrent movers %s to %s",
property, newVal), rootException);
throw rootException;
}
}
break;
}
} else if (property.equals(
DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_KEY)) {
ReconfigurationException rootException = null;
try {
LOG.info("Reconfiguring " + property + " to " + newVal);
int movers;
if (newVal == null) {
// set to default
movers = DFS_DATANODE_BALANCE_MAX_NUM_CONCURRENT_MOVES_DEFAULT;
} else {
movers = Integer.parseInt(newVal);
if (movers <= 0) {
rootException = new ReconfigurationException(
property,
newVal,
getConf().get(property),
new IllegalArgumentException(
"balancer max concurrent movers must be larger than 0"));
}
}
xserver.updateBalancerMaxConcurrentMovers(movers);
} catch(NumberFormatException nfe) {
rootException = new ReconfigurationException(
property, newVal, getConf().get(property), nfe);
} finally {
if (rootException != null) {
LOG.warn(String.format(
"Exception in updating balancer max concurrent movers %s to %s",
property, newVal), rootException);
throw rootException;
}
}
} else {
throw new ReconfigurationException(
property, newVal, getConf().get(property));
default:
break;
}
throw new ReconfigurationException(
property, newVal, getConf().get(property));
}
/**

46
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeHotSwapVolumes.java
View File

@ -284,7 +284,10 @@ private void addVolumes(int numNewVolumes)
}
String newDataDir = newDataDirBuf.toString();
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, newDataDir);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, newDataDir),
is(conf.get(DFS_DATANODE_DATA_DIR_KEY)));
// Verify the configuration value is appropriately set.
String[] effectiveDataDirs = conf.get(DFS_DATANODE_DATA_DIR_KEY).split(",");
@ -447,8 +450,11 @@ public void testRemoveOneVolume()
DataNode dn = cluster.getDataNodes().get(0);
Collection<String> oldDirs = getDataDirs(dn);
String newDirs = oldDirs.iterator().next(); // Keep the first volume.
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, newDirs);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, newDirs),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
assertFileLocksReleased(
new ArrayList<String>(oldDirs).subList(1, oldDirs.size()));
dn.scheduleAllBlockReport(0);
@ -504,8 +510,11 @@ public void testReplicatingAfterRemoveVolume()
newDirs = dir;
break;
}
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, newDirs);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, newDirs),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
oldDirs.remove(newDirs);
assertFileLocksReleased(oldDirs);
@ -651,8 +660,10 @@ public Object answer(InvocationOnMock invocation)
public void run() {
try {
barrier.await();
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, newDirs);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, newDirs),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
} catch (ReconfigurationException |
InterruptedException |
BrokenBarrierException e) {
@ -700,7 +711,10 @@ public void testAddBackRemovedVolume()
String keepDataDir = oldDataDir.split(",")[0];
String removeDataDir = oldDataDir.split(",")[1];
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, keepDataDir);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, keepDataDir),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
for (int i = 0; i < cluster.getNumNameNodes(); i++) {
String bpid = cluster.getNamesystem(i).getBlockPoolId();
BlockPoolSliceStorage bpsStorage =
@ -717,7 +731,10 @@ public void testAddBackRemovedVolume()
// Bring the removed directory back. It only successes if all metadata about
// this directory were removed from the previous step.
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, oldDataDir);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, oldDataDir),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
}
/** Get the FsVolume on the given basePath */
@ -771,7 +788,10 @@ public void testDirectlyReloadAfterCheckDiskError()
assertEquals(used, failedVolume.getDfsUsed());
DataNodeTestUtils.restoreDataDirFromFailure(dirToFail);
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, oldDataDir);
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, oldDataDir),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
createFile(new Path("/test2"), 32, (short)2);
FsVolumeImpl restoredVolume = getVolume(dn, dirToFail);
@ -805,7 +825,11 @@ public void testFullBlockReportAfterRemovingVolumes()
// Remove a data dir from datanode
File dataDirToKeep = new File(cluster.getDataDirectory(), "data1");
dn.reconfigurePropertyImpl(DFS_DATANODE_DATA_DIR_KEY, dataDirToKeep.toString());
assertThat(
"DN did not update its own config",
dn.reconfigurePropertyImpl(
DFS_DATANODE_DATA_DIR_KEY, dataDirToKeep.toString()),
is(dn.getConf().get(DFS_DATANODE_DATA_DIR_KEY)));
// We should get 1 full report
Mockito.verify(spy, timeout(60000).times(1)).blockReport(

21
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailure.java
View File

@ -17,10 +17,12 @@
*/
package org.apache.hadoop.hdfs.server.datanode;
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;
import static org.junit.Assume.assumeTrue;
@ -322,13 +324,17 @@ public void testVolumeFailureRecoveredByHotSwappingVolume()
// Hot swap out the failure volume.
String dataDirs = dn0Vol2.getPath();
dn0.reconfigurePropertyImpl(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
dataDirs);
assertThat(
dn0.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, dataDirs),
is(dn0.getConf().get(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY)));
// Fix failure volume dn0Vol1 and remount it back.
DataNodeTestUtils.restoreDataDirFromFailure(dn0Vol1);
dn0.reconfigurePropertyImpl(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
oldDataDirs);
assertThat(
dn0.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY, oldDataDirs),
is(dn0.getConf().get(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY)));
// Fail dn0Vol2. Now since dn0Vol1 has been fixed, DN0 has sufficient
// resources, thus it should keep running.
@ -352,8 +358,11 @@ public void testTolerateVolumeFailuresAfterAddingMoreVolumes()
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY);
// Add a new volume to DN0
dn0.reconfigurePropertyImpl(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
oldDataDirs + "," + dn0VolNew.getAbsolutePath());
assertThat(
dn0.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
oldDataDirs + "," + dn0VolNew.getAbsolutePath()),
is(dn0.getConf().get(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY)));
// Fail dn0Vol1 first and hot swap it.
DataNodeTestUtils.injectDataDirFailure(dn0Vol1);

9
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDataNodeVolumeFailureReporting.java
View File

@ -19,9 +19,11 @@
import static org.apache.hadoop.test.MetricsAsserts.assertCounter;
import static org.apache.hadoop.test.MetricsAsserts.getMetrics;
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;
import static org.junit.Assume.assumeTrue;
@ -591,8 +593,11 @@ private static void reconfigureDataNode(DataNode dn, File... newVols)
dnNewDataDirs.append(newVol.getAbsolutePath());
}
try {
dn.reconfigurePropertyImpl(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
dnNewDataDirs.toString());
assertThat(
dn.reconfigurePropertyImpl(
DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY,
dnNewDataDirs.toString()),
is(dn.getConf().get(DFSConfigKeys.DFS_DATANODE_DATA_DIR_KEY)));
} catch (ReconfigurationException e) {
// This can be thrown if reconfiguration tries to use a failed volume.
// We need to swallow the exception, because some of our tests want to