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https://issues.apache.org/jira/browse/HDFS-16155?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17395057#comment-17395057
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Hadoop QA commented on HDFS-16155:
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|| Vote || Subsystem || Runtime || Logfile || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 17m
20s{color} | | {color:blue} Docker mode activated. {color} |
|| || || || {color:brown} Prechecks {color} || ||
| {color:green}+1{color} | {color:green} dupname {color} | {color:green} 0m
0s{color} | | {color:green} No case conflicting files found. {color} |
| {color:blue}0{color} | {color:blue} codespell {color} | {color:blue} 0m
0s{color} | | {color:blue} codespell was not available. {color} |
| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m
0s{color} | | {color:green} The patch does not contain any @author tags.
{color} |
| {color:green}+1{color} | {color:green} test4tests {color} | {color:green} 0m
0s{color} | | {color:green} The patch appears to include 2 new or modified
test files. {color} |
|| || || || {color:brown} trunk Compile Tests {color} || ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 12m
40s{color} | | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 23m
5s{color} | | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 5m
16s{color} | | {color:green} trunk passed with JDK
Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04 {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 4m
52s{color} | | {color:green} trunk passed with JDK Private
Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10 {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 1m
14s{color} | | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} mvnsite {color} | {color:green} 2m
16s{color} | | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m
35s{color} | | {color:green} trunk passed with JDK
Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04 {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 2m
2s{color} | | {color:green} trunk passed with JDK Private
Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10 {color} |
| {color:green}+1{color} | {color:green} spotbugs {color} | {color:green} 5m
51s{color} | | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} shadedclient {color} | {color:green}
18m 59s{color} | | {color:green} branch has no errors when building and
testing our client artifacts. {color} |
|| || || || {color:brown} Patch Compile Tests {color} || ||
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue} 0m
23s{color} | | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 2m
1s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 5m
10s{color} | | {color:green} the patch passed with JDK
Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04 {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 5m
10s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 4m
49s{color} | | {color:green} the patch passed with JDK Private
Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10 {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 4m
49s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} blanks {color} | {color:green} 0m
0s{color} | | {color:green} The patch has no blanks issues. {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 1m
8s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} mvnsite {color} | {color:green} 2m
7s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} xml {color} | {color:green} 0m
1s{color} | | {color:green} The patch has no ill-formed XML file. {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m
22s{color} | | {color:green} the patch passed with JDK
Ubuntu-11.0.11+9-Ubuntu-0ubuntu2.20.04 {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 1m
46s{color} | | {color:green} the patch passed with JDK Private
Build-1.8.0_292-8u292-b10-0ubuntu1~20.04-b10 {color} |
| {color:green}+1{color} | {color:green} spotbugs {color} | {color:green} 5m
54s{color} | | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} shadedclient {color} | {color:green}
18m 28s{color} | | {color:green} patch has no errors when building and testing
our client artifacts. {color} |
|| || || || {color:brown} Other Tests {color} || ||
| {color:green}+1{color} | {color:green} unit {color} | {color:green} 2m
14s{color} | | {color:green} hadoop-hdfs-client in the patch passed. {color} |
| {color:red}-1{color} | {color:red} unit {color} | {color:red}337m 15s{color}
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[/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt|https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3271/4/artifact/out/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt]
| {color:red} hadoop-hdfs in the patch passed. {color} |
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m
39s{color} | | {color:green} The patch does not generate ASF License warnings.
{color} |
| {color:black}{color} | {color:black} {color} | {color:black}476m 17s{color} |
| {color:black}{color} |
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|| Reason || Tests ||
| Failed junit tests | hadoop.hdfs.server.namenode.TestDecommissioningStatus |
| | hadoop.hdfs.server.namenode.TestDecommissioningStatusWithBackoffMonitor |
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|| Subsystem || Report/Notes ||
| Docker | ClientAPI=1.41 ServerAPI=1.41 base:
https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3271/4/artifact/out/Dockerfile
|
| GITHUB PR | https://github.com/apache/hadoop/pull/3271 |
| JIRA Issue | HDFS-16155 |
| Optional Tests | dupname asflicense compile javac javadoc mvninstall mvnsite
unit shadedclient spotbugs checkstyle codespell xml |
| uname | Linux 686f6ed0e729 4.15.0-147-generic #151-Ubuntu SMP Fri Jun 18
19:21:19 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | dev-support/bin/hadoop.sh |
| git revision | trunk / 400b7995fea10fb926c825e529c6b23142c4619a |
| 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-3271/4/testReport/ |
| Max. process+thread count | 1900 (vs. ulimit of 5500) |
| modules | C: hadoop-hdfs-project/hadoop-hdfs-client
hadoop-hdfs-project/hadoop-hdfs U: hadoop-hdfs-project |
| Console output |
https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-3271/4/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.
> Allow configurable exponential backoff in DFSInputStream refetchLocations
> -------------------------------------------------------------------------
>
> Key: HDFS-16155
> URL: https://issues.apache.org/jira/browse/HDFS-16155
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: dfsclient
> Reporter: Bryan Beaudreault
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 50m
> Remaining Estimate: 0h
>
> The retry policy in
> [DFSInputStream#refetchLocations|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L1018-L1040]
> was first written many years ago. It allows configuration of the base time
> window, but subsequent retries double in an un-configurable way. This retry
> strategy makes sense in some clusters as it's very conservative and will
> avoid DDOSing the namenode in certain systemic failure modes – for example,
> if a file is being read by a large hadoop job and the underlying blocks are
> moved by the balancer. In this case, enough datanodes would be added to the
> deadNodes list and all hadoop tasks would simultaneously try to refetch the
> blocks. The 3s doubling with random factor helps break up that stampeding
> herd.
> However, not all cluster use-cases are created equal, so there are other
> cases where a more aggressive initial backoff is preferred. For example in a
> low-latency single reader scenario. In this case, if the balancer moves
> enough blocks, the reader hits this 3s backoff which is way too long for a
> low latency use-case.
> One could configure the the window very low (10ms), but then you can hit
> other systemic failure modes which would result in readers DDOSing the
> namenode again. For example, if blocks went missing due to truly dead
> datanodes. In this case, many readers might be refetching locations for
> different files with retry backoffs like 10ms, 20ms, 40ms, etc. It takes a
> while to backoff enough to avoid impacting the namenode with that strategy.
> I suggest adding a configurable multiplier to the backoff strategy so that
> operators can tune this as they see fit for their use-case. In the above low
> latency case, one could set the base very low (say 2ms) and the multiplier
> very high (say 50). This gives an aggressive first retry that very quickly
> backs off.
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