HDFS-16401.Remove the worthless DatasetVolumeChecker#numAsyncDatasetChecks.

[jianghuazhu]

Description of PR

It seems that cleaning up DatasetVolumeChecker#numAsyncDatasetChecks was ignored before this.
Details: HDFS-16401

How was this patch tested?

For testing, there is not much pressure.

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 56s		Docker mode activated.
			_ Prechecks _
+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 doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch.
			_ trunk Compile Tests _
+1 💚	mvninstall	35m 42s		trunk passed
+1 💚	compile	1m 27s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	compile	1m 23s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	checkstyle	0m 59s		trunk passed
+1 💚	mvnsite	1m 28s		trunk passed
+1 💚	javadoc	1m 0s		trunk passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 28s		trunk passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	3m 19s		trunk passed
+1 💚	shadedclient	26m 7s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 23s		the patch passed
+1 💚	compile	1m 28s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javac	1m 28s		the patch passed
+1 💚	compile	1m 22s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	javac	1m 22s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 57s		the patch passed
+1 💚	mvnsite	1m 28s		the patch passed
+1 💚	javadoc	0m 55s		the patch passed with JDK Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 26s		the patch passed with JDK Private Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10
+1 💚	spotbugs	3m 50s		the patch passed
+1 💚	shadedclient	28m 21s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	352m 35s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 43s		The patch does not generate ASF License warnings.
		465m 25s

Reason	Tests
Failed junit tests	hadoop.hdfs.server.blockmanagement.TestBlockTokenWithShortCircuitRead

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3838/1/artifact/out/Dockerfile
GITHUB PR	#3838
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux 1e404f18216c 4.15.0-162-generic #170-Ubuntu SMP Mon Oct 18 11:38:05 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 58092d0
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-3838/1/testReport/
Max. process+thread count	2029 (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-3838/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0-SNAPSHOT https://yetus.apache.org

This message was automatically generated.

[jianghuazhu]

Some failed unit tests were found in UT, such as:
TestBlockTokenWithShortCircuitRead
TestBlockTokenWithShortCircuitRead
TestBlockScanner
TestFileTruncate
TestEditLogTailer
TestReencryptionWithKMS

It seems that these failures have little to do with my changes.
Can you help review this pr @ayushtkn @tomscut .
Thank you very much.

[tomscut]

After HDFS-11279, numAsyncDatasetChecks is not used.

LGTM.

[jianghuazhu]

Thanks @tomscut .

[jianghuazhu]

Can you help review this pr, @jojochuang @ferhui .
Thank you very much.

[jianghuazhu]

Thanks @ferhui .

[ayushtkn]

LGTM.

[jianghuazhu]

Thanks @ayushtkn .

[jianghuazhu]

Hi @ferhui , can this pr be merged into trunk branch or other main branch?
If not for now, I will continue to work hard.
Thank you very much.

[ferhui]

@jianghuazhu Thanks for your contribution. @ayushtkn Thanks for your review! Merged.