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HADOOP-17596. ABFS: Change default Readahead Queue Depth from num(processors) to const #3106

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Merged
merged 2 commits into from
Jul 10, 2021
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HADOOP-17596. ABFS: Change default Readahead Queue Depth from num(processors) to const #3106

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HADOOP-17596. ABFS: Change default Readahead Queue Depth from num(pro…
sumangala-patki Jun 3, 2021
5ab045b
trigger yetus
sumangala17 Jun 17, 2021
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2 changes: 1 addition & 1 deletion ...azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/FileSystemConfigurations.java
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Expand Up @@ -88,7 +88,7 @@ public final class FileSystemConfigurations {
public static final int MIN_LEASE_DURATION = 15;
public static final int MAX_LEASE_DURATION = 60;

public static final int DEFAULT_READ_AHEAD_QUEUE_DEPTH = -1;
public static final int DEFAULT_READ_AHEAD_QUEUE_DEPTH = 2;

public static final boolean DEFAULT_ENABLE_FLUSH = true;
public static final boolean DEFAULT_DISABLE_OUTPUTSTREAM_FLUSH = true;
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2 changes: 1 addition & 1 deletion hadoop-tools/hadoop-azure/src/site/markdown/abfs.md
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Expand Up @@ -803,7 +803,7 @@ pattern is detected.
`fs.azure.readaheadqueue.depth`: Sets the readahead queue depth in
AbfsInputStream. In case the set value is negative the read ahead queue depth
will be set as Runtime.getRuntime().availableProcessors(). By default the value
will be -1. To disable readaheads, set this value to 0. If your workload is
will be 2. To disable readaheads, set this value to 0. If your workload is
doing only random reads (non-sequential) or you are seeing throttling, you
may try setting this value to 0.

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16 changes: 16 additions & 0 deletions ...adoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/services/TestAbfsInputStream.java
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Expand Up @@ -28,6 +28,7 @@

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.Path;
Expand All @@ -48,6 +49,7 @@

import static org.apache.hadoop.test.LambdaTestUtils.intercept;
import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.FORWARD_SLASH;
import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.FS_AZURE_READ_AHEAD_QUEUE_DEPTH;

/**
* Unit test AbfsInputStream.
Expand Down Expand Up @@ -569,6 +571,20 @@ public void testDiffReadRequestSizeAndRAHBlockSize() throws Exception {
testReadAheads(inputStream, FORTY_EIGHT_KB, SIXTEEN_KB);
}

@Test
public void testDefaultReadaheadQueueDepth() throws Exception {
Configuration config = getRawConfiguration();
config.unset(FS_AZURE_READ_AHEAD_QUEUE_DEPTH);
AzureBlobFileSystem fs = getFileSystem(config);
Path testFile = new Path("/testFile");
fs.create(testFile);
FSDataInputStream in = fs.open(testFile);
Assertions.assertThat(
((AbfsInputStream) in.getWrappedStream()).getReadAheadQueueDepth())
.describedAs("readahead queue depth should be set to default value 2")
.isEqualTo(2);
}


private void testReadAheads(AbfsInputStream inputStream,
int readRequestSize,
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