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HADOOP-18528. Disable abfs prefetching by default (#5134) 

Disables block prefetching on ABFS InputStreams, by setting
fs.azure.enable.readahead to false in core-default.xml and
the matching java constant.

This prevents
HADOOP-18521. ABFS ReadBufferManager buffer sharing across concurrent HTTP requests.

Once a fix for that is committed, this change can be reverted.

Contributed by Mehakmeet Singh.
This commit is contained in:
Mehakmeet Singh 2022-11-15 19:58:41 +05:30 committed by Steve Loughran
parent 033ceca090
commit 9e53ed3602
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GPG Key ID: D22CF846DBB162A0
5 changed files with 13 additions and 2 deletions
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7
hadoop-common-project/hadoop-common/src/main/resources/core-default.xml
View File

@ -2141,6 +2141,13 @@ The switch to turn S3A auditing on or off.
<description>The AbstractFileSystem for gs: uris.</description>
</property>
<property>
<name>fs.azure.enable.readahead</name>
<value>false</value>
<description>Disable readahead/prefetching in AbfsInputStream.
See HADOOP-18521</description>
</property>
<property>
<name>io.seqfile.compress.blocksize</name>
<value>1000000</value>

2
hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/FileSystemConfigurations.java
View File

@ -106,7 +106,7 @@ public final class FileSystemConfigurations {
public static final boolean DEFAULT_ABFS_LATENCY_TRACK = false;
public static final long DEFAULT_SAS_TOKEN_RENEW_PERIOD_FOR_STREAMS_IN_SECONDS = 120;
public static final boolean DEFAULT_ENABLE_READAHEAD = true;
public static final boolean DEFAULT_ENABLE_READAHEAD = false;
public static final String DEFAULT_FS_AZURE_USER_AGENT_PREFIX = EMPTY_STRING;
public static final String DEFAULT_VALUE_UNKNOWN = "UNKNOWN";

2
hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsInputStreamContext.java
View File

@ -35,7 +35,7 @@ public class AbfsInputStreamContext extends AbfsStreamContext {
private boolean tolerateOobAppends;
private boolean isReadAheadEnabled = true;
private boolean isReadAheadEnabled = false;
private boolean alwaysReadBufferSize;

2
hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/contract/ITestAbfsFileSystemContractSeek.java
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@ -34,6 +34,7 @@ import org.apache.hadoop.fs.contract.AbstractFSContract;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.AZURE_READ_AHEAD_RANGE;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.AZURE_READ_BUFFER_SIZE;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.FS_AZURE_ENABLE_READAHEAD;
import static org.apache.hadoop.fs.azurebfs.constants.FileSystemConfigurations.MIN_BUFFER_SIZE;
import static org.apache.hadoop.fs.contract.ContractTestUtils.createFile;
import static org.apache.hadoop.fs.contract.ContractTestUtils.dataset;
@ -68,6 +69,7 @@ public class ITestAbfsFileSystemContractSeek extends AbstractContractSeekTest{
protected AbstractFSContract createContract(final Configuration conf) {
conf.setInt(AZURE_READ_AHEAD_RANGE, MIN_BUFFER_SIZE);
conf.setInt(AZURE_READ_BUFFER_SIZE, MIN_BUFFER_SIZE);
conf.setBoolean(FS_AZURE_ENABLE_READAHEAD, true);
return new AbfsFileSystemContract(conf, isSecure);
}

2
hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/services/TestAbfsInputStream.java
View File

@ -106,6 +106,7 @@ public class TestAbfsInputStream extends
private AbfsInputStream getAbfsInputStream(AbfsClient mockAbfsClient,
String fileName) throws IOException {
AbfsInputStreamContext inputStreamContext = new AbfsInputStreamContext(-1);
inputStreamContext.isReadAheadEnabled(true);
// Create AbfsInputStream with the client instance
AbfsInputStream inputStream = new AbfsInputStream(
mockAbfsClient,
@ -131,6 +132,7 @@ public class TestAbfsInputStream extends
boolean alwaysReadBufferSize,
int readAheadBlockSize) throws IOException {
AbfsInputStreamContext inputStreamContext = new AbfsInputStreamContext(-1);
inputStreamContext.isReadAheadEnabled(true);
// Create AbfsInputStream with the client instance
AbfsInputStream inputStream = new AbfsInputStream(
abfsClient,