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Posted to common-issues@hadoop.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2024/03/07 06:05:00 UTC
[jira] [Commented] (HADOOP-19052) Hadoop use Shell command to get the count of the hard link which takes a lot of time
[ https://issues.apache.org/jira/browse/HADOOP-19052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17824262#comment-17824262 ]
ASF GitHub Bot commented on HADOOP-19052:
-----------------------------------------
hadoop-yetus commented on PR #6587:
URL: https://github.com/apache/hadoop/pull/6587#issuecomment-1982488808
:broken_heart: **-1 overall**
| Vote | Subsystem | Runtime | Logfile | Comment |
|:----:|----------:|--------:|:--------:|:-------:|
| +0 :ok: | reexec | 0m 48s | | Docker mode activated. |
|||| _ Prechecks _ |
| +1 :green_heart: | dupname | 0m 0s | | No case conflicting files found. |
| +0 :ok: | codespell | 0m 1s | | codespell was not available. |
| +0 :ok: | detsecrets | 0m 1s | | detect-secrets was not available. |
| +1 :green_heart: | @author | 0m 0s | | The patch does not contain any @author tags. |
| +1 :green_heart: | test4tests | 0m 0s | | The patch appears to include 1 new or modified test files. |
|||| _ trunk Compile Tests _ |
| +1 :green_heart: | mvninstall | 49m 18s | | trunk passed |
| +1 :green_heart: | compile | 19m 18s | | trunk passed with JDK Ubuntu-11.0.22+7-post-Ubuntu-0ubuntu220.04.1 |
| +1 :green_heart: | compile | 17m 30s | | trunk passed with JDK Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| +1 :green_heart: | checkstyle | 1m 17s | | trunk passed |
| +1 :green_heart: | mvnsite | 1m 39s | | trunk passed |
| +1 :green_heart: | javadoc | 1m 15s | | trunk passed with JDK Ubuntu-11.0.22+7-post-Ubuntu-0ubuntu220.04.1 |
| +1 :green_heart: | javadoc | 0m 49s | | trunk passed with JDK Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| -1 :x: | spotbugs | 2m 35s | [/branch-spotbugs-hadoop-common-project_hadoop-common-warnings.html](https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6587/4/artifact/out/branch-spotbugs-hadoop-common-project_hadoop-common-warnings.html) | hadoop-common-project/hadoop-common in trunk has 1 extant spotbugs warnings. |
| +1 :green_heart: | shadedclient | 39m 34s | | branch has no errors when building and testing our client artifacts. |
|||| _ Patch Compile Tests _ |
| +1 :green_heart: | mvninstall | 0m 55s | | the patch passed |
| +1 :green_heart: | compile | 18m 14s | | the patch passed with JDK Ubuntu-11.0.22+7-post-Ubuntu-0ubuntu220.04.1 |
| +1 :green_heart: | javac | 18m 14s | | the patch passed |
| +1 :green_heart: | compile | 17m 16s | | the patch passed with JDK Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| +1 :green_heart: | javac | 17m 16s | | the patch passed |
| +1 :green_heart: | blanks | 0m 0s | | The patch has no blanks issues. |
| -0 :warning: | checkstyle | 1m 12s | [/results-checkstyle-hadoop-common-project_hadoop-common.txt](https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6587/4/artifact/out/results-checkstyle-hadoop-common-project_hadoop-common.txt) | hadoop-common-project/hadoop-common: The patch generated 2 new + 42 unchanged - 0 fixed = 44 total (was 42) |
| +1 :green_heart: | mvnsite | 1m 36s | | the patch passed |
| +1 :green_heart: | javadoc | 1m 8s | | the patch passed with JDK Ubuntu-11.0.22+7-post-Ubuntu-0ubuntu220.04.1 |
| +1 :green_heart: | javadoc | 0m 50s | | the patch passed with JDK Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| +1 :green_heart: | spotbugs | 2m 40s | | the patch passed |
| +1 :green_heart: | shadedclient | 39m 45s | | patch has no errors when building and testing our client artifacts. |
|||| _ Other Tests _ |
| +1 :green_heart: | unit | 19m 18s | | hadoop-common in the patch passed. |
| +1 :green_heart: | asflicense | 0m 59s | | The patch does not generate ASF License warnings. |
| | | 241m 42s | | |
| Subsystem | Report/Notes |
|----------:|:-------------|
| Docker | ClientAPI=1.44 ServerAPI=1.44 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6587/4/artifact/out/Dockerfile |
| GITHUB PR | https://github.com/apache/hadoop/pull/6587 |
| Optional Tests | dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets |
| uname | Linux 7a9555771181 5.15.0-94-generic #104-Ubuntu SMP Tue Jan 9 15:25:40 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | dev-support/bin/hadoop.sh |
| git revision | trunk / 5153bde137794615f2f948f9f713966cb6653462 |
| Default Java | Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| Multi-JDK versions | /usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.22+7-post-Ubuntu-0ubuntu220.04.1 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_392-8u392-ga-1~20.04-b08 |
| Test Results | https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-6587/4/testReport/ |
| Max. process+thread count | 1449 (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-6587/4/console |
| versions | git=2.25.1 maven=3.6.3 spotbugs=4.2.2 |
| Powered by | Apache Yetus 0.14.0 https://yetus.apache.org |
This message was automatically generated.
> Hadoop use Shell command to get the count of the hard link which takes a lot of time
> ------------------------------------------------------------------------------------
>
> Key: HADOOP-19052
> URL: https://issues.apache.org/jira/browse/HADOOP-19052
> Project: Hadoop Common
> Issue Type: Improvement
> Environment: Hadopp 3.3.4
> Reporter: liang yu
> Priority: Major
> Labels: pull-request-available
> Attachments: debuglog.png
>
>
> Using Hadoop 3.3.4
>
> When the QPS of `append` executions is very high, at a rate of above 10000/s.
>
> We found that the write speed in hadoop is very slow. We traced some datanodes' log and find that there is a warning :
> {code:java}
> 2024-01-26 11:09:44,292 WARN impl.FsDatasetImpl (InstrumentedLock.java:logwaitWarning(165)) Waited above threshold(300 ms) to acquire lock: lock identifier: FsDatasetRwlock waitTimeMs=336 ms.Suppressed 0 lock wait warnings.Longest supressed waitTimeMs=0.The stack trace is
> java.lang.Thread,getStackTrace(Thread.java:1559)
> org.apache.hadoop.util.StringUtils.getStackTrace(StringUtils.java:1060)
> org.apache.hadoop.util.Instrumentedlock.logWaitWarning(InstrumentedLock.java:171)
> org.apache.hadoop.util.InstrumentedLock.check(InstrumentedLock.java:222)
> org.apache.hadoop.util.InstrumentedLock.lock(InstrumentedLock, iaya:105)
> org.apache.hadoop.util.AutocloseableLock.acquire(AutocloseableLock.java:67)
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.append(FsDatasetImpl.java:1239)
> org.apache.hadoop.hdfs.server.datanode.BlockReceiver.<init>(BlockReceiver.java:230)
> org.apache.hadoop.hdfs.server.datanode.DataXceiver.getBlockReceiver (DataXceiver.java:1313)
> org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock (DataXceiver.java:764)
> org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.opWriteBlock(Receiver.java:176)
> org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.processOp(Receiver.java:110)
> org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:293)
> java.lang.Thread.run(Thread.java:748)
> {code}
>
> Then we traced the method _org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.append(FsDatasetImpl. java:1239),_ and print how long each command take to finish the execution, and find that it takes us 700ms to get the linkCount of the file which is really slow.
> !debuglog.png!
>
> We traced the code and find that java1.8 use a Shell Command to get the linkCount, in which execution it will start a new Process and wait for the Process to fork, when the QPS is very high, it will sometimes take a long time to fork the process.
> Here is the shell command.
> {code:java}
> stat -c%h /path/to/file
> {code}
>
> Solution:
> For the FileStore that supports the file attributes "unix", we can use the method _Files.getAttribute(f.toPath(), "unix:nlink")_ to get the linkCount, this method doesn't need to start a new process, and will return the result in a very short time.
>
> When we use this method to get the file linkCount, we rarely get the WARN log above when the QPS of append execution is high.
> .
>
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