HDFS-16505. Setting safemode should not be interrupted by abnormal nodes

[tomscut]

JIRA: HDFS-16505.

Setting safemode should not be interrupted by abnormal nodes.

For example, we have four namenodes configured in the following order:
NS1 -> active
NS2 -> standby
NS3 -> observer
NS4 -> observer.

When the NS1 process exits, setting the states of safemode, NS2, NS3, and NS4 fails. Similarly, when the NS2 process exits, only the safemode state of NS1 can be set successfully.

When the NS1 process exits:
Before the change:

After the change:

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	17m 37s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		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	36m 7s		trunk passed
+1 💚	compile	1m 30s		trunk passed with JDK Ubuntu-11.0.14+9-Ubuntu-0ubuntu2.20.04
+1 💚	compile	1m 21s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	checkstyle	0m 59s		trunk passed
+1 💚	mvnsite	1m 28s		trunk passed
+1 💚	javadoc	1m 3s		trunk passed with JDK Ubuntu-11.0.14+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 31s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 23s		trunk passed
+1 💚	shadedclient	25m 40s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 19s		the patch passed
+1 💚	compile	1m 25s		the patch passed with JDK Ubuntu-11.0.14+9-Ubuntu-0ubuntu2.20.04
+1 💚	javac	1m 25s		the patch passed
+1 💚	compile	1m 14s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	javac	1m 14s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 53s		the patch passed
+1 💚	mvnsite	1m 20s		the patch passed
+1 💚	javadoc	0m 55s		the patch passed with JDK Ubuntu-11.0.14+9-Ubuntu-0ubuntu2.20.04
+1 💚	javadoc	1m 27s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 28s		the patch passed
+1 💚	shadedclient	25m 56s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	319m 0s		hadoop-hdfs in the patch passed.
+1 💚	asflicense	0m 38s		The patch does not generate ASF License warnings.
		445m 12s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4071/1/artifact/out/Dockerfile
GITHUB PR	#4071
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux 593f24028593 4.15.0-163-generic #171-Ubuntu SMP Fri Nov 5 11:55:11 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / fe6bbea
Default Java	Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.14+9-Ubuntu-0ubuntu2.20.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4071/1/testReport/
Max. process+thread count	2325 (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-4071/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[tomscut]

Hi @jojochuang @ayushtkn @Hexiaoqiao @ferhui , could you please take a look? Thanks.

[ferhui]

+1

[ferhui]

I see there were some comments on the jira ticket. we can discuss on that ticket firstly.

[github-actions]

We're closing this stale PR because it has been open for 100 days with no activity. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you feel like this was a mistake, or you would like to continue working on it, please feel free to re-open it and ask for a committer to remove the stale tag and review again.
Thanks all for your contribution.