HDFS-17865. Prevent updateNameDirSize() from blocking rollEditLog()

[kokonguyen191]

Description of PR

updateNameDirSize() has only metrics functionality (i.e. not very critical) but has a fair bit of performance impact in one of the more critical methods (rollEditLog). It's better to either reduce the metrics update frequency or make it update asynchronously to avoid interference with rollEditLog().

How was this patch tested?

UT, and production environment.

Before

After

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	12m 19s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+0 🆗	detsecrets	0m 1s		detect-secrets 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	23m 29s		trunk passed
+1 💚	compile	0m 48s		trunk passed with JDK Ubuntu-21.0.7+6-Ubuntu-0ubuntu120.04
+1 💚	compile	0m 46s		trunk passed with JDK Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
+1 💚	checkstyle	0m 29s		trunk passed
+1 💚	mvnsite	0m 52s		trunk passed
+1 💚	javadoc	0m 42s		trunk passed with JDK Ubuntu-21.0.7+6-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 41s		trunk passed with JDK Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
+1 💚	spotbugs	2m 2s		trunk passed
+1 💚	shadedclient	15m 45s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 47s		the patch passed
+1 💚	compile	0m 41s		the patch passed with JDK Ubuntu-21.0.7+6-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 41s		the patch passed
+1 💚	compile	0m 44s		the patch passed with JDK Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
+1 💚	javac	0m 44s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 23s		the patch passed
+1 💚	mvnsite	0m 46s		the patch passed
+1 💚	javadoc	0m 32s		the patch passed with JDK Ubuntu-21.0.7+6-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 33s		the patch passed with JDK Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
-1 ❌	spotbugs	2m 3s	/new-spotbugs-hadoop-hdfs-project_hadoop-hdfs.html	hadoop-hdfs-project/hadoop-hdfs generated 1 new + 0 unchanged - 0 fixed = 1 total (was 0)
+1 💚	shadedclient	16m 2s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	173m 7s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 24s		The patch does not generate ASF License warnings.
		255m 55s

Reason	Tests
SpotBugs	module:hadoop-hdfs-project/hadoop-hdfs
	new org.apache.hadoop.hdfs.server.namenode.NNStorage(Configuration, Collection, Collection) invokes org.apache.hadoop.hdfs.server.namenode.NNStorage$NameDirSizeMapUpdateService.start() At NNStorage.java:org.apache.hadoop.hdfs.server.namenode.NNStorage$NameDirSizeMapUpdateService.start() At NNStorage.java:[line 188]
Failed junit tests	hadoop.hdfs.tools.TestDFSAdmin

Subsystem	Report/Notes
Docker	ClientAPI=1.52 ServerAPI=1.52 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8144/1/artifact/out/Dockerfile
GITHUB PR	#8144
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 42b14e7cc4c3 5.15.0-164-generic #174-Ubuntu SMP Fri Nov 14 20:25:16 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / ee7eea1
Default Java	Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
Multi-JDK versions	/usr/lib/jvm/java-21-openjdk-amd64:Ubuntu-21.0.7+6-Ubuntu-0ubuntu120.04 /usr/lib/jvm/java-17-openjdk-amd64:Ubuntu-17.0.15+6-Ubuntu-0ubuntu120.04
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-8144/1/testReport/
Max. process+thread count	4133 (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-8144/1/console
versions	git=2.25.1 maven=3.9.11 spotbugs=4.9.7
Powered by	Apache Yetus 0.14.0 https://yetus.apache.org

This message was automatically generated.