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HDFS-12482. Provide a configuration to adjust the weight of EC recovery tasks to adjust the speed of recovery. (lei)

This commit is contained in:
Lei Xu 2017-10-31 21:58:14 -07:00
parent ed24da3dd7
commit 9367c25dbd
7 changed files with 106 additions and 1 deletions
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4
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
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@ -596,6 +596,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
public static final int DFS_DN_EC_RECONSTRUCTION_STRIPED_READ_TIMEOUT_MILLIS_DEFAULT = 5000; //5s
public static final String DFS_DN_EC_RECONSTRUCTION_THREADS_KEY = "dfs.datanode.ec.reconstruction.threads";
public static final int DFS_DN_EC_RECONSTRUCTION_THREADS_DEFAULT = 8;
public static final String DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_KEY =
"dfs.datanode.ec.reconstruction.xmits.weight";
public static final float DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_DEFAULT =
0.5f;
public static final String
DFS_DATANODE_DIRECTORYSCAN_THROTTLE_LIMIT_MS_PER_SEC_KEY =

6
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNodeFaultInjector.java
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@ -89,4 +89,10 @@ public void endOfferService() throws Exception {}
public void throwTooManyOpenFiles() throws FileNotFoundException {
}
/**
* Used as a hook to inject failure in erasure coding reconstruction
* process.
*/
public void stripedBlockReconstruction() throws IOException {}
}

12
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/ErasureCodingWorker.java
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@ -17,6 +17,7 @@
*/
package org.apache.hadoop.hdfs.server.datanode.erasurecode;
import com.google.common.base.Preconditions;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSConfigKeys;
@ -47,6 +48,7 @@ public final class ErasureCodingWorker {
private final DataNode datanode;
private final Configuration conf;
private final float xmitWeight;
private ThreadPoolExecutor stripedReconstructionPool;
private ThreadPoolExecutor stripedReadPool;
@ -54,6 +56,14 @@ public final class ErasureCodingWorker {
public ErasureCodingWorker(Configuration conf, DataNode datanode) {
this.datanode = datanode;
this.conf = conf;
this.xmitWeight = conf.getFloat(
DFSConfigKeys.DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_KEY,
DFSConfigKeys.DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_DEFAULT
);
Preconditions.checkArgument(this.xmitWeight >= 0,
"Invalid value configured for " +
DFSConfigKeys.DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_KEY +
", it can not be negative value (" + this.xmitWeight + ").");
initializeStripedReadThreadPool();
initializeStripedBlkReconstructionThreadPool(conf.getInt(
@ -128,7 +138,7 @@ public void processErasureCodingTasks(
// 1) NN will not send more tasks than what DN can execute and
// 2) DN will not throw away reconstruction tasks, and instead keeps
// an unbounded number of tasks in the executor's task queue.
xmitsSubmitted = task.getXmits();
xmitsSubmitted = Math.max((int)(task.getXmits() * xmitWeight), 1);
getDatanode().incrementXmitsInProcess(xmitsSubmitted);
stripedReconstructionPool.submit(task);
} else {

2
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/erasurecode/StripedBlockReconstructor.java
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@ -21,6 +21,7 @@
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.server.datanode.DataNodeFaultInjector;
import org.apache.hadoop.hdfs.server.datanode.metrics.DataNodeMetrics;
import org.apache.hadoop.util.Time;
@ -80,6 +81,7 @@ public void run() {
void reconstruct() throws IOException {
while (getPositionInBlock() < getMaxTargetLength()) {
DataNodeFaultInjector.get().stripedBlockReconstruction();
long remaining = getMaxTargetLength() - getPositionInBlock();
final int toReconstructLen =
(int) Math.min(getStripedReader().getBufferSize(), remaining);

13
hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
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@ -3072,6 +3072,19 @@
</description>
</property>
<property>
<name>dfs.datanode.ec.reconstruction.xmits.weight</name>
<value>0.5</value>
<description>
Datanode uses xmits weight to calculate the relative cost of EC recovery
tasks comparing to replicated block recovery, of which xmits is always 1.
Namenode then uses xmits reported from datanode to throttle recovery tasks
for EC and replicated blocks.
The xmits of an erasure coding recovery task is calculated as the maximum
value between the number of read streams and the number of write streams.
</description>
</property>
<property>
<name>dfs.namenode.quota.init-threads</name>
<value>4</value>

6
hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSErasureCoding.md
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@ -136,6 +136,12 @@ Deployment
1. `dfs.datanode.ec.reconstruction.stripedread.timeout.millis` - Timeout for striped reads. Default value is 5000 ms.
1. `dfs.datanode.ec.reconstruction.stripedread.buffer.size` - Buffer size for reader service. Default value is 64KB.
1. `dfs.datanode.ec.reconstruction.threads` - Number of threads used by the Datanode for background reconstruction work. Default value is 8 threads.
1. `dfs.datanode.ec.reconstruction.xmits.weight` - Relative weight of xmits used by EC background recovery task comparing to replicated block recovery. Default value is 0.5.
It sets to `0` to disable calculate weights for EC recovery tasks, that is, EC task always has `1` xmits.
The xmits of an erasure coding recovery task is calculated as the maximum value between the number of read streams and the number of write streams. For example, if an EC recovery
task need to read from 6 nodes and write to 2 nodes, it has xmits of `max(6, 2) * 0.5 = 3`. Recovery task for replicated file always counts
as `1` xmit. NameNode utilizes `dfs.namenode.replication.max-streams` minus the total `xmitsInProgress` on the DataNode that combines of the xmits from
replicated file and EC files, to schedule recovery tasks to this DataNode.
### Enable Intel ISA-L

64
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestReconstructStripedFile.java
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@ -30,6 +30,8 @@
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
@ -45,6 +47,7 @@
import org.apache.hadoop.hdfs.server.blockmanagement.BlockManagerTestUtil;
import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeStorageInfo;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.datanode.DataNodeFaultInjector;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.protocol.DatanodeStorage;
import org.apache.hadoop.hdfs.server.protocol.BlockECReconstructionCommand.BlockECReconstructionInfo;
@ -53,6 +56,7 @@
import org.apache.hadoop.io.erasurecode.ErasureCodeNative;
import org.apache.hadoop.io.erasurecode.rawcoder.NativeRSRawErasureCoderFactory;
import org.apache.hadoop.test.GenericTestUtils;
import org.apache.hadoop.test.LambdaTestUtils;
import org.apache.log4j.Level;
import org.junit.After;
import org.junit.Assert;
@ -488,4 +492,64 @@ private void testNNSendsErasureCodingTasks(int deadDN) throws Exception {
500, 30000
);
}
@Test(timeout = 180000)
public void testErasureCodingWorkerXmitsWeight() throws Exception {
testErasureCodingWorkerXmitsWeight(1f, ecPolicy.getNumDataUnits());
testErasureCodingWorkerXmitsWeight(0f, 1);
testErasureCodingWorkerXmitsWeight(10f, 10 * ecPolicy.getNumDataUnits());
}
private void testErasureCodingWorkerXmitsWeight(
float weight, int expectedWeight)
throws Exception {
// Reset cluster with customized xmits weight.
conf.setFloat(DFSConfigKeys.DFS_DN_EC_RECONSTRUCTION_XMITS_WEIGHT_KEY,
weight);
cluster.shutdown();
cluster = new MiniDFSCluster.Builder(conf).numDataNodes(dnNum).build();
cluster.waitActive();
fs = cluster.getFileSystem();
fs.enableErasureCodingPolicy(
StripedFileTestUtil.getDefaultECPolicy().getName());
fs.getClient().setErasureCodingPolicy("/",
StripedFileTestUtil.getDefaultECPolicy().getName());
final int fileLen = cellSize * ecPolicy.getNumDataUnits() * 2;
writeFile(fs, "/ec-xmits-weight", fileLen);
DataNode dn = cluster.getDataNodes().get(0);
int corruptBlocks = dn.getFSDataset().getFinalizedBlocks(
cluster.getNameNode().getNamesystem().getBlockPoolId()).size();
int expectedXmits = corruptBlocks * expectedWeight;
final CyclicBarrier barrier = new CyclicBarrier(corruptBlocks + 1);
DataNodeFaultInjector oldInjector = DataNodeFaultInjector.get();
DataNodeFaultInjector delayInjector = new DataNodeFaultInjector() {
public void stripedBlockReconstruction() throws IOException {
try {
barrier.await();
} catch (InterruptedException | BrokenBarrierException e) {
throw new IOException(e);
}
}
};
DataNodeFaultInjector.set(delayInjector);
try {
shutdownDataNode(dn);
LambdaTestUtils.await(30 * 1000, 500,
() -> {
int totalXmits = cluster.getDataNodes().stream()
.mapToInt(DataNode::getXmitsInProgress).sum();
return totalXmits == expectedXmits;
}
);
} finally {
barrier.await();
DataNodeFaultInjector.set(oldInjector);
}
}
}