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HDFS-16520. Improve EC pread: avoid potential reading whole block (#4104) 

Reviewed-by: Hui Fei <ferhui@apache.org>
Reviewed-by: Takanobu Asanuma <tasanuma@apache.org>
Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>
(cherry picked from commit 29401c8203)
This commit is contained in:
daimin 2022-05-07 01:30:32 +08:00 committed by Wei-Chiu Chuang
parent 4d935eaed7
commit d711d200fe
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GPG Key ID: B362E1C021854B9D
4 changed files with 92 additions and 3 deletions
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4
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClientFaultInjector.java
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@ -22,6 +22,7 @@
import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
/**
* Used for injecting faults in DFSClient and DFSOutputStream tests.
@ -65,4 +66,7 @@ public boolean skipRollingRestartWait() {
public void sleepBeforeHedgedGet() {}
public void delayWhenRenewLeaseTimeout() {}
public void onCreateBlockReader(LocatedBlock block, int chunkIndex, long offset, long length) {}
}

15
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java
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@ -234,7 +234,7 @@ private long getOffsetInBlockGroup(long pos) {
boolean createBlockReader(LocatedBlock block, long offsetInBlock,
LocatedBlock[] targetBlocks, BlockReaderInfo[] readerInfos,
int chunkIndex) throws IOException {
int chunkIndex, long readTo) throws IOException {
BlockReader reader = null;
final ReaderRetryPolicy retry = new ReaderRetryPolicy();
DFSInputStream.DNAddrPair dnInfo =
@ -252,9 +252,14 @@ boolean createBlockReader(LocatedBlock block, long offsetInBlock,
if (dnInfo == null) {
break;
}
if (readTo < 0 || readTo > block.getBlockSize()) {
readTo = block.getBlockSize();
}
reader = getBlockReader(block, offsetInBlock,
block.getBlockSize() - offsetInBlock,
readTo - offsetInBlock,
dnInfo.addr, dnInfo.storageType, dnInfo.info);
DFSClientFaultInjector.get().onCreateBlockReader(block, chunkIndex, offsetInBlock,
readTo - offsetInBlock);
} catch (IOException e) {
if (e instanceof InvalidEncryptionKeyException &&
retry.shouldRefetchEncryptionKey()) {
@ -489,11 +494,16 @@ protected void fetchBlockByteRange(LocatedBlock block, long start,
final LocatedBlock[] blks = StripedBlockUtil.parseStripedBlockGroup(
blockGroup, cellSize, dataBlkNum, parityBlkNum);
final BlockReaderInfo[] preaderInfos = new BlockReaderInfo[groupSize];
long readTo = -1;
for (AlignedStripe stripe : stripes) {
readTo = Math.max(readTo, stripe.getOffsetInBlock() + stripe.getSpanInBlock());
}
try {
for (AlignedStripe stripe : stripes) {
// Parse group to get chosen DN location
StripeReader preader = new PositionStripeReader(stripe, ecPolicy, blks,
preaderInfos, corruptedBlocks, decoder, this);
preader.setReadTo(readTo);
try {
preader.readStripe();
} finally {
@ -558,4 +568,5 @@ public synchronized void unbuffer() {
parityBuf = null;
}
}
}

8
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/StripeReader.java
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@ -119,6 +119,7 @@ void skip() {
protected final int cellSize;
protected final RawErasureDecoder decoder;
protected final DFSStripedInputStream dfsStripedInputStream;
private long readTo = -1;
protected ECChunk[] decodeInputs;
@ -302,7 +303,7 @@ boolean readChunk(final LocatedBlock block, int chunkIndex)
if (readerInfos[chunkIndex] == null) {
if (!dfsStripedInputStream.createBlockReader(block,
alignedStripe.getOffsetInBlock(), targetBlocks,
readerInfos, chunkIndex)) {
readerInfos, chunkIndex, readTo)) {
chunk.state = StripingChunk.MISSING;
return false;
}
@ -480,4 +481,9 @@ void clearFutures() {
boolean useDirectBuffer() {
return decoder.preferDirectBuffer();
}
public void setReadTo(long readTo) {
this.readTo = readTo;
}
}

68
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSStripedInputStream.java
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@ -49,7 +49,9 @@
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_DEFAULT;
@ -664,4 +666,70 @@ public void testUnbuffer() throws Exception {
assertNull(in.parityBuf);
in.close();
}
@Test
public void testBlockReader() throws Exception {
ecPolicy = StripedFileTestUtil.getDefaultECPolicy(); // RS-6-3-1024k
int fileSize = 19 * cellSize + 100;
long stripeSize = (long) dataBlocks * cellSize;
byte[] bytes = StripedFileTestUtil.generateBytes(fileSize);
DFSTestUtil.writeFile(fs, filePath, new String(bytes));
try (DFSStripedInputStream in =
(DFSStripedInputStream) fs.getClient().open(filePath.toString())) {
// Verify pread:
verifyPreadRanges(in, 0, 2 * cellSize,
2 * cellSize, Arrays.asList("0_0_1048576", "1_0_1048576"));
verifyPreadRanges(in, 0, 5 * cellSize + 9527,
5 * cellSize + 9527, Arrays.asList("0_0_1048576", "1_0_1048576",
"2_0_1048576", "3_0_1048576", "4_0_1048576", "5_0_1048576"));
verifyPreadRanges(in, 100, 5 * cellSize + 9527,
5 * cellSize + 9527, Arrays.asList("0_100_1048476", "1_0_1048576",
"2_0_1048576", "3_0_1048576", "4_0_1048576", "5_0_1048576"));
verifyPreadRanges(in, stripeSize * 3, 2 * cellSize,
cellSize + 100, Arrays.asList("0_1048576_1048576", "1_1048576_100"));
// Verify sread:
verifySreadRanges(in, 0, Arrays.asList("0_0_2097152", "1_0_2097152",
"2_0_2097152", "3_0_2097152", "4_0_2097152", "5_0_2097152"));
verifySreadRanges(in, stripeSize * 2, Arrays.asList("0_0_2097152", "1_0_1048676",
"2_0_1048576", "3_0_1048576", "4_0_1048576", "5_0_1048576"));
}
}
private void verifyPreadRanges(DFSStripedInputStream in, long position,
int length, int lengthExpected,
List<String> rangesExpected) throws Exception {
List<String> ranges = new ArrayList<>(); // range format: chunkIndex_offset_len
DFSClientFaultInjector.set(new DFSClientFaultInjector() {
@Override
public void onCreateBlockReader(LocatedBlock block, int chunkIndex,
long offset, long length) {
ranges.add(String.format("%s_%s_%s", chunkIndex, offset, length));
}
});
assertEquals(lengthExpected, in.read(position, new byte[length], 0, length));
Collections.sort(ranges);
Collections.sort(rangesExpected);
assertEquals(rangesExpected, ranges);
}
private void verifySreadRanges(DFSStripedInputStream in, long position,
List<String> rangesExpected) throws Exception {
List<String> ranges = new ArrayList<>(); // range format: chunkIndex_offset_len
DFSClientFaultInjector.set(new DFSClientFaultInjector() {
@Override
public void onCreateBlockReader(LocatedBlock block, int chunkIndex,
long offset, long length) {
ranges.add(String.format("%s_%s_%s", chunkIndex, offset, length));
}
});
in.seek(position);
int length = in.read(new byte[1024]);
assertEquals(1024, length);
Collections.sort(ranges);
Collections.sort(rangesExpected);
assertEquals(rangesExpected, ranges);
}
}