HDFS-16168. Fix TestHDFSFileSystemContract.testAppend timeout

[secfree]

Description of PR

1. Fix random timeout failures of TestHDFSFileSystemContract.testAppend

How was this patch tested?

1. UT

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?

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 50s		Docker mode activated.
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+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ trunk Compile Tests _
+1 💚	mvninstall	33m 33s		trunk passed
+1 💚	compile	1m 29s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	compile	1m 24s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	checkstyle	1m 1s		trunk passed
+1 💚	mvnsite	1m 30s		trunk passed
+1 💚	javadoc	1m 1s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 34s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	3m 21s		trunk passed
+1 💚	shadedclient	23m 21s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 26s		the patch passed
+1 💚	compile	1m 25s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javac	1m 25s		the patch passed
+1 💚	compile	1m 19s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	javac	1m 19s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 55s		the patch passed
+1 💚	mvnsite	1m 23s		the patch passed
+1 💚	javadoc	0m 59s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 31s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	3m 44s		the patch passed
+1 💚	shadedclient	24m 31s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	229m 6s		hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 47s		The patch does not generate ASF License warnings.
		333m 24s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3815/1/artifact/out/Dockerfile
GITHUB PR	#3815
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux 87bd3d88e402 4.15.0-58-generic #64-Ubuntu SMP Tue Aug 6 11:12:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 1bfc3fb
Default Java	Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3815/1/testReport/
Max. process+thread count	3591 (vs. ulimit of 5500)
modules	C: hadoop-hdfs-project/hadoop-hdfs U: hadoop-hdfs-project/hadoop-hdfs
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3815/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[ayushtkn]

Changes LGTM

[ferhui]

@secfree Thanks for your contribution, it looks good, will merge this if no other comments.
BTW, as you mentioned in jira, FileSystemContractBaseTest affects all its sub classes. Maybe you can check whether other test cases except the one here are affected and resolve them if they are affected.

[ferhui]

@secfree Thanks for your contribution. @ayushtkn Thanks for your review!

[secfree]

@secfree Thanks for your contribution, it looks good, will merge this if no other comments. BTW, as you mentioned in jira, FileSystemContractBaseTest affects all its sub classes. Maybe you can check whether other test cases except the one here are affected and resolve them if they are affected.

@ferhui thanks for your suggestion. I checked all sub classes of FileSystemContractBaseTest and found one more case. Here is the details: https://issues.apache.org/jira/browse/HDFS-16392