HADOOP-18528. Disable readAhead/prefetching by default

[mehakmeet]

Description of PR

Setting readAhead config to false by default.

How was this patch tested?

Region: us-west-2
mvn -Dparallel-tests=abfs -DtestsThreadCount=8 -Dscale clean verify

Seeing some timeout errors, going to test the latest ABFS trunk code to see the differences tomorrow.

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[steveloughran]

where do you test it?

• @snvijaya @anmolanmol1234 @pranavsaxena-microsoft

what do you all think? this is us disabling the readahead so we can get on with the real fix without being in a rush and really trying to get the tests together. that should include taking the AbfsInputStream test, have it create real CSV rows (use my mkcsv code as a foundation) and then have use the mapreduce TextInputFormat code to read it back across multiple threads, just have hive and spark do

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 50s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+0 🆗	xmllint	0m 0s		xmllint was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 2 new or modified test files.
			_ trunk Compile Tests _
+0 🆗	mvndep	16m 3s		Maven dependency ordering for branch
+1 💚	mvninstall	26m 30s		trunk passed
+1 💚	compile	23m 33s		trunk passed with JDK Ubuntu-11.0.16+8-post-Ubuntu-0ubuntu120.04
+1 💚	compile	20m 51s		trunk passed with JDK Private Build-1.8.0_342-8u342-b07-0ubuntu1~20.04-b07
+1 💚	checkstyle	4m 20s		trunk passed
+1 💚	mvnsite	3m 10s		trunk passed
+1 💚	javadoc	2m 26s		trunk passed with JDK Ubuntu-11.0.16+8-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	2m 15s		trunk passed with JDK Private Build-1.8.0_342-8u342-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	4m 34s		trunk passed
+1 💚	shadedclient	21m 49s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+0 🆗	mvndep	0m 25s		Maven dependency ordering for patch
+1 💚	mvninstall	1m 38s		the patch passed
+1 💚	compile	22m 33s		the patch passed with JDK Ubuntu-11.0.16+8-post-Ubuntu-0ubuntu120.04
+1 💚	javac	22m 33s		the patch passed
+1 💚	compile	20m 53s		the patch passed with JDK Private Build-1.8.0_342-8u342-b07-0ubuntu1~20.04-b07
+1 💚	javac	20m 53s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	4m 1s		the patch passed
+1 💚	mvnsite	3m 19s		the patch passed
+1 💚	javadoc	2m 31s		the patch passed with JDK Ubuntu-11.0.16+8-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	2m 23s		the patch passed with JDK Private Build-1.8.0_342-8u342-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	4m 58s		the patch passed
+1 💚	shadedclient	22m 1s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	18m 53s		hadoop-common in the patch passed.
+1 💚	unit	2m 51s		hadoop-azure in the patch passed.
+1 💚	asflicense	1m 19s		The patch does not generate ASF License warnings.
		238m 48s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5134/1/artifact/out/Dockerfile
GITHUB PR	#5134
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient codespell detsecrets xmllint spotbugs checkstyle
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Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 3981da0
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modules	C: hadoop-common-project/hadoop-common hadoop-tools/hadoop-azure U: .
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[mukund-thakur]

Looks good. Should we backport the test as well that I have added internally?

[mehakmeet]

Okay, ran the test suite on trunk as well. There are no additional errors/failures after the changes, it's showing some errors on the base version.

[ERROR] testGetIsNamespaceEnabledWhenConfigIsTrue(org.apache.hadoop.fs.azurebfs.ITestGetNameSpaceEnabled)  Time elapsed: 3.876 s  <<< FAILURE!
org.junit.ComparisonFailure: [getIsNamespaceEnabled should return the value configured for fs.azure.test.namespace.enabled] expected:<[fals]e> but was:<[tru]e>
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

Not sure why this is a failure and not just skipping the test in case the config isn't set.

[ERROR] Tests run: 13, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 82.967 s <<< FAILURE! - in org.apache.hadoop.fs.azurebfs.ITestAzureBlobFileSystemLease
[ERROR] testTwoCreate(org.apache.hadoop.fs.azurebfs.ITestAzureBlobFileSystemLease)  Time elapsed: 6.501 s  <<< FAILURE!
java.lang.AssertionError: 
 Expected to find 'There is currently a lease on the resource and no lease ID was specified in the request' but got unexpected exception: org.apache.hadoop.fs.PathIOException: `abfs://abfs-testcontainer-f5fe9b62-0253-4a90-af0a-d43bd5970d24@mmtusw.dfs.core.windows.net/fork-0001/test/testTwoCreatedec41fc7870b/testfile': Input/output error: Parallel access to the create path detected. Failing request to honor single writer semantics
	at org.apache.hadoop.fs.azurebfs.AzureBlobFileSystem.checkException(AzureBlobFileSystem.java:1500)
	at org.apache.hadoop.fs.azurebfs.AzureBlobFileSystem.create(AzureBlobFileSystem.java:331)
	at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:1231)
...

Caused by: Parallel access to the create path detected. Failing request to honor single writer semantics
	at org.apache.hadoop.fs.azurebfs.AzureBlobFileSystemStore.conditionalCreateOverwriteFile(AzureBlobFileSystemStore.java:652)
	at org.apache.hadoop.fs.azurebfs.AzureBlobFileSystemStore.createFile(AzureBlobFileSystemStore.java:563)

Seeing it fail as a stand-alone test as well.

[WARNING] Tests run: 48, Failures: 0, Errors: 0, Skipped: 24, Time elapsed: 396.823 s - in org.apache.hadoop.fs.azurebfs.ITestSmallWriteOptimization
[ERROR] Tests run: 10, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 725.369 s <<< FAILURE! - in org.apache.hadoop.fs.azurebfs.ITestAbfsReadWriteAndSeek
[ERROR] testReadAndWriteWithDifferentBufferSizesAndSeek[Size=104,857,600-readahead=true](org.apache.hadoop.fs.azurebfs.ITestAbfsReadWriteAndSeek)  Time elapsed: 670.478 s  <<< FAILURE!
org.junit.ComparisonFailure: [Retry was required due to issue on server side] expected:<[0]> but was:<[1]>
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

Intermittent failure, saw this in trunk once.

Also had a timeout error in ITestAbfsTerasort.

[steveloughran]

the lease one plays up on me, as does ITestSmallWriteOptimization; especially on parallel runs. i'm not worried there