HADOOP-17462: Hadoop Client getRpcResponse May Return Wrong Result

[belugabehr]

The done variable is not marked as volatile so the thread which is checking its status is free to cache the value and never reload it even though it is expected to change by a different thread. The while loop may be stuck waiting for the change, but is always looking at a cached value. If that happens, timeout will occur and then return 'null'.

In previous versions of Hadoop, there was no time-out at this level, so it would cause endless loop. Really tough error to track down if it happens.

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	1m 4s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+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 15s		trunk passed
+1 💚	compile	21m 32s		trunk passed with JDK Ubuntu-11.0.9.1+1-Ubuntu-0ubuntu1.18.04
+1 💚	compile	18m 8s		trunk passed with JDK Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
+1 💚	checkstyle	0m 48s		trunk passed
+1 💚	mvnsite	1m 26s		trunk passed
+1 💚	shadedclient	19m 44s		branch has no errors when building and testing our client artifacts.
+1 💚	javadoc	0m 57s		trunk passed with JDK Ubuntu-11.0.9.1+1-Ubuntu-0ubuntu1.18.04
+1 💚	javadoc	1m 27s		trunk passed with JDK Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
+0 🆗	spotbugs	2m 21s		Used deprecated FindBugs config; considering switching to SpotBugs.
+1 💚	findbugs	2m 18s		trunk passed
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 53s		the patch passed
+1 💚	compile	20m 50s		the patch passed with JDK Ubuntu-11.0.9.1+1-Ubuntu-0ubuntu1.18.04
+1 💚	javac	20m 50s		the patch passed
+1 💚	compile	18m 4s		the patch passed with JDK Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
+1 💚	javac	18m 4s		the patch passed
-0 ⚠️	checkstyle	0m 46s	/diff-checkstyle-hadoop-common-project_hadoop-common.txt	hadoop-common-project/hadoop-common: The patch generated 1 new + 98 unchanged - 1 fixed = 99 total (was 99)
+1 💚	mvnsite	1m 24s		the patch passed
+1 💚	whitespace	0m 0s		The patch has no whitespace issues.
+1 💚	shadedclient	16m 58s		patch has no errors when building and testing our client artifacts.
+1 💚	javadoc	0m 57s		the patch passed with JDK Ubuntu-11.0.9.1+1-Ubuntu-0ubuntu1.18.04
+1 💚	javadoc	1m 28s		the patch passed with JDK Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
+1 💚	findbugs	2m 22s		the patch passed
			_ Other Tests _
+1 💚	unit	9m 55s		hadoop-common in the patch passed.
+1 💚	asflicense	0m 46s		The patch does not generate ASF License warnings.
		179m 25s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2610/1/artifact/out/Dockerfile
GITHUB PR	#2610
JIRA Issue	HADOOP-17462
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient findbugs checkstyle
uname	Linux 916223cd519b 4.15.0-126-generic #129-Ubuntu SMP Mon Nov 23 18:53:38 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / e306f59
Default Java	Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.9.1+1-Ubuntu-0ubuntu1.18.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_275-8u275-b01-0ubuntu1~18.04-b01
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2610/1/testReport/
Max. process+thread count	2239 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-common U: hadoop-common-project/hadoop-common
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2610/1/console
versions	git=2.17.1 maven=3.6.0 findbugs=4.0.6
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