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https://issues.apache.org/jira/browse/HDFS-6782?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14525877#comment-14525877
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Hadoop QA commented on HDFS-6782:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | pre-patch | 14m 58s | Pre-patch trunk compilation is
healthy. |
| {color:green}+1{color} | @author | 0m 0s | The patch does not contain any
@author tags. |
| {color:red}-1{color} | tests included | 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. |
| {color:green}+1{color} | javac | 7m 46s | There were no new javac warning
messages. |
| {color:green}+1{color} | javadoc | 9m 55s | There were no new javadoc
warning messages. |
| {color:green}+1{color} | release audit | 0m 22s | The applied patch does
not increase the total number of release audit warnings. |
| {color:green}+1{color} | checkstyle | 2m 18s | There were no new checkstyle
issues. |
| {color:red}-1{color} | whitespace | 0m 0s | The patch has 3 line(s) that
end in whitespace. Use git apply --whitespace=fix. |
| {color:green}+1{color} | install | 1m 35s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse | 0m 34s | The patch built with
eclipse:eclipse. |
| {color:green}+1{color} | findbugs | 3m 7s | The patch does not introduce
any new Findbugs (version 2.0.3) warnings. |
| {color:green}+1{color} | native | 3m 19s | Pre-build of native portion |
| {color:green}+1{color} | hdfs tests | 165m 55s | Tests passed in hadoop-hdfs.
|
| | | 209m 54s | |
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|| Subsystem || Report/Notes ||
| Patch URL |
http://issues.apache.org/jira/secure/attachment/12659525/HDFS-6782.002.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / a319771 |
| whitespace |
https://builds.apache.org/job/PreCommit-HDFS-Build/10745/artifact/patchprocess/whitespace.txt
|
| hadoop-hdfs test log |
https://builds.apache.org/job/PreCommit-HDFS-Build/10745/artifact/patchprocess/testrun_hadoop-hdfs.txt
|
| Test Results |
https://builds.apache.org/job/PreCommit-HDFS-Build/10745/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf904.gq1.ygridcore.net 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 |
| Console output |
https://builds.apache.org/job/PreCommit-HDFS-Build/10745/console |
This message was automatically generated.
> Improve FS editlog logSync
> --------------------------
>
> Key: HDFS-6782
> URL: https://issues.apache.org/jira/browse/HDFS-6782
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.4.1
> Reporter: Yi Liu
> Assignee: Yi Liu
> Attachments: HDFS-6782.001.patch, HDFS-6782.002.patch
>
>
> In NN, it uses a double buffer (bufCurrent, bufReady) for log sync,
> bufCurrent it to buffer new coming edit ops and bufReady is for flushing.
> This's efficient. When flush is ongoing, and bufCurrent is full, NN goes to
> force log sync, and all new Ops are blocked (since force log sync is
> protected by FSNameSystem write lock). After the flush finished, the new Ops
> are still blocked, but actually at this time, bufCurrent is free and Ops can
> go ahead and write to the buffer. The following diagram shows the detail.
> This JIRA is for this improvement. Thanks [~umamaheswararao] for confirming
> this issue.
> {code}
> edit1(txid1) ------ write to bufCurrent -------- logSync --------- (swap
> buffer)flushing -------
> edit2(txid2) ------ write to bufCurrent -------- logSync --------- waiting
> -------
> edit3(txid3) ------ write to bufCurrent -------- logSync --------- waiting
> -------
> edit4(txid4) ------ write to bufCurrent -------- logSync --------- waiting
> -------
> edit5(txid5) ------ write to bufCurrent --full-- force sync --------- waiting
> -------
> edit6(txid6) ------ blocked
> ...
> editn(txidn) ------ blocked
> {code}
> After the flush, it becomes
> {code}
> edit1(txid1) ------ write to bufCurrent -------- logSync --------- finished
> --------
> edit2(txid2) ------ write to bufCurrent -------- logSync --------- flushing
> -------
> edit3(txid3) ------ write to bufCurrent -------- logSync --------- waiting
> -------
> edit4(txid4) ------ write to bufCurrent -------- logSync --------- waiting
> -------
> edit5(txid5) ------ write to bufCurrent --full-- force sync --------- waiting
> -------
> edit6(txid6) ------ blocked
> ...
> editn(txidn) ------ blocked
> {code}
> After edit1 finished, bufCurrent is free, and the thread which flushes txid2
> will also flushes txid3-5, so we should return from the force sync of edit5
> and FSNamesystem write lock will be freed (Don't worry that edit5 Op will
> return, since there will be a normal logSync after the force logSync and
> there will wait for sync finished). This is the idea of this JIRA.
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