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Posted to common-issues@hadoop.apache.org by "Hadoop QA (JIRA)" <ji...@apache.org> on 2016/06/30 21:20:11 UTC

[jira] [Commented] (HADOOP-12077) Provide a multi-URI replication Inode for ViewFs

    [ https://issues.apache.org/jira/browse/HADOOP-12077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15357872#comment-15357872 ] 

Hadoop QA commented on HADOOP-12077:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue}  0m 26s{color} | {color:blue} Docker mode activated. {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 3 new or modified test files. {color} |
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue}  0m 33s{color} | {color:blue} Maven dependency ordering for branch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  6m 49s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  7m  0s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green}  1m 23s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} mvnsite {color} | {color:green}  1m 51s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green}  0m 27s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green}  3m 17s{color} | {color:green} trunk passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  1m 46s{color} | {color:green} trunk passed {color} |
| {color:blue}0{color} | {color:blue} mvndep {color} | {color:blue}  0m 14s{color} | {color:blue} Maven dependency ordering for patch {color} |
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green}  1m 35s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green}  6m 54s{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} javac {color} | {color:red}  6m 54s{color} | {color:red} root generated 1 new + 708 unchanged - 0 fixed = 709 total (was 708) {color} |
| {color:orange}-0{color} | {color:orange} checkstyle {color} | {color:orange}  1m 26s{color} | {color:orange} root: The patch generated 7 new + 180 unchanged - 8 fixed = 187 total (was 188) {color} |
| {color:green}+1{color} | {color:green} mvnsite {color} | {color:green}  1m 57s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} mvneclipse {color} | {color:green}  0m 34s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green}  0m  0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:red}-1{color} | {color:red} findbugs {color} | {color:red}  1m 40s{color} | {color:red} hadoop-common-project/hadoop-common generated 4 new + 0 unchanged - 0 fixed = 4 total (was 0) {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green}  2m  0s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} unit {color} | {color:green}  7m 31s{color} | {color:green} hadoop-common in the patch passed. {color} |
| {color:red}-1{color} | {color:red} unit {color} | {color:red} 58m 39s{color} | {color:red} hadoop-hdfs in the patch failed. {color} |
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green}  0m 35s{color} | {color:green} The patch does not generate ASF License warnings. {color} |
| {color:black}{color} | {color:black} {color} | {color:black}131m 20s{color} | {color:black} {color} |
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|| Reason || Tests ||
| FindBugs | module:hadoop-common-project/hadoop-common |
|  |  Boxing/unboxing to parse a primitive org.apache.hadoop.fs.viewfs.NflyFSystem.createFileSystem(URI[], Configuration, String)  At NflyFSystem.java:org.apache.hadoop.fs.viewfs.NflyFSystem.createFileSystem(URI[], Configuration, String)  At NflyFSystem.java:[line 933] |
|  |  org.apache.hadoop.fs.viewfs.NflyFSystem$MRNflyNode doesn't override org.apache.hadoop.net.NodeBase.equals(Object)  At NflyFSystem.java:At NflyFSystem.java:[line 1] |
|  |  org.apache.hadoop.fs.viewfs.NflyFSystem$NflyNode doesn't override org.apache.hadoop.net.NodeBase.equals(Object)  At NflyFSystem.java:At NflyFSystem.java:[line 1] |
|  |  org.apache.hadoop.fs.viewfs.NflyFSystem$NflyStatus overrides equals in org.apache.hadoop.fs.FileStatus and may not be symmetric  At NflyFSystem.java:and may not be symmetric  At NflyFSystem.java:[lines 523-526] |
| Failed junit tests | hadoop.hdfs.tools.offlineEditsViewer.TestOfflineEditsViewer |
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|| Subsystem || Report/Notes ||
| Docker |  Image:yetus/hadoop:85209cc |
| JIRA Patch URL | https://issues.apache.org/jira/secure/attachment/12798359/HADOOP-12077.005.patch |
| JIRA Issue | HADOOP-12077 |
| Optional Tests |  asflicense  compile  javac  javadoc  mvninstall  mvnsite  unit  findbugs  checkstyle  |
| uname | Linux fed46bb3cdce 3.13.0-36-lowlatency #63-Ubuntu SMP PREEMPT Wed Sep 3 21:56:12 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | /testptch/hadoop/patchprocess/precommit/personality/provided.sh |
| git revision | trunk / 846ada2 |
| Default Java | 1.8.0_91 |
| findbugs | v3.0.0 |
| javac | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/artifact/patchprocess/diff-compile-javac-root.txt |
| checkstyle | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/artifact/patchprocess/diff-checkstyle-root.txt |
| findbugs | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/artifact/patchprocess/new-findbugs-hadoop-common-project_hadoop-common.html |
| unit | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/artifact/patchprocess/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt |
|  Test Results | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/testReport/ |
| modules | C: hadoop-common-project/hadoop-common hadoop-hdfs-project/hadoop-hdfs U: . |
| Console output | https://builds.apache.org/job/PreCommit-HADOOP-Build/9908/console |
| Powered by | Apache Yetus 0.4.0-SNAPSHOT   http://yetus.apache.org |


This message was automatically generated.



> Provide a multi-URI replication Inode for ViewFs
> ------------------------------------------------
>
>                 Key: HADOOP-12077
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12077
>             Project: Hadoop Common
>          Issue Type: New Feature
>          Components: fs
>            Reporter: Gera Shegalov
>            Assignee: Gera Shegalov
>         Attachments: HADOOP-12077.001.patch, HADOOP-12077.002.patch, HADOOP-12077.003.patch, HADOOP-12077.004.patch, HADOOP-12077.005.patch
>
>
> This JIRA is to provide simple "replication" capabilities for applications that maintain logically equivalent paths in multiple locations for caching or failover (e.g., S3 and HDFS). We noticed a simple common HDFS usage pattern in our applications. They host their data on some logical cluster C. There are corresponding HDFS clusters in multiple datacenters. When the application runs in DC1, it prefers to read from C in DC1, and the applications prefers to failover to C in DC2 if the application is migrated to DC2 or when C in DC1 is unavailable. New application data versions are created periodically/relatively infrequently. 
> In order to address many common scenarios in a general fashion, and to avoid unnecessary code duplication, we implement this functionality in ViewFs (our default FileSystem spanning all clusters in all datacenters) in a project code-named Nfly (N as in N datacenters). Currently each ViewFs Inode points to a single URI via ChRootedFileSystem. Consequently, we introduce a new type of links that points to a list of URIs that are each going to be wrapped in ChRootedFileSystem. A typical usage: /nfly/C/user->/DC1/C/user,/DC2/C/user,... This collection of ChRootedFileSystem instances is fronted by the Nfly filesystem object that is actually used for the mount point/Inode. Nfly filesystems backs a single logical path /nfly/C/user/<user>/path by multiple physical paths.
> Nfly filesystem supports setting minReplication. As long as the number of URIs on which an update has succeeded is greater than or equal to minReplication exceptions are only logged but not thrown. Each update operation is currently executed serially (client-bandwidth driven parallelism will be added later). 
> A file create/write: 
> # Creates a temporary invisible _nfly_tmp_file in the intended chrooted filesystem. 
> # Returns a FSDataOutputStream that wraps output streams returned by 1
> # All writes are forwarded to each output stream.
> # On close of stream created by 2, all n streams are closed, and the files are renamed from _nfly_tmp_file to file. All files receive the same mtime corresponding to the client system time as of beginning of this step. 
> # If at least minReplication destinations has gone through steps 1-4 without failures the transaction is considered logically committed, otherwise a best-effort attempt of cleaning up the temporary files is attempted.
> As for reads, we support a notion of locality similar to HDFS  /DC/rack/node. We sort Inode URIs using NetworkTopology by their authorities. These are typically host names in simple HDFS URIs. If the authority is missing as is the case with the local file:/// the local host name is assumed InetAddress.getLocalHost(). This makes sure that the local file system is always the closest one to the reader in this approach. For our Hadoop 2 hdfs URIs that are based on nameservice ids instead of hostnames it is very easy to adjust the topology script since our nameservice ids already contain the datacenter. As for rack and node we can simply output any string such as /DC/rack-nsid/node-nsid, since we only care about datacenter-locality for such filesystem clients.
> There are 2 policies/additions to the read call path that makes it more expensive, but improve user experience:
> - readMostRecent - when this policy is enabled, Nfly first checks mtime for the path under all URIs, sorts them from most recent to least recent. Nfly then sorts the set of most recent URIs topologically in the same manner as described above.
> - repairOnRead - when readMostRecent is enabled Nfly already has to RPC all underlying destinations. With repairOnRead, Nfly filesystem would additionally attempt to refresh destinations with the path missing or a stale version of the path using the nearest available most recent destination. 



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