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https://issues.apache.org/jira/browse/HDFS-8859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14661761#comment-14661761
]
Hadoop QA commented on HDFS-8859:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:red}-1{color} | pre-patch | 15m 46s | Findbugs (version ) appears to
be broken on trunk. |
| {color:green}+1{color} | @author | 0m 0s | The patch does not contain any
@author tags. |
| {color:green}+1{color} | tests included | 0m 0s | The patch appears to
include 1 new or modified test files. |
| {color:green}+1{color} | javac | 7m 41s | There were no new javac warning
messages. |
| {color:green}+1{color} | javadoc | 9m 40s | There were no new javadoc
warning messages. |
| {color:green}+1{color} | release audit | 0m 23s | The applied patch does
not increase the total number of release audit warnings. |
| {color:green}+1{color} | checkstyle | 1m 14s | There were no new checkstyle
issues. |
| {color:red}-1{color} | whitespace | 0m 0s | The patch has 2 line(s) that
end in whitespace. Use git apply --whitespace=fix. |
| {color:green}+1{color} | install | 1m 30s | mvn install still works. |
| {color:green}+1{color} | eclipse:eclipse | 0m 32s | The patch built with
eclipse:eclipse. |
| {color:green}+1{color} | findbugs | 4m 24s | The patch does not introduce
any new Findbugs (version 3.0.0) warnings. |
| {color:red}-1{color} | common tests | 22m 31s | Tests failed in
hadoop-common. |
| {color:red}-1{color} | hdfs tests | 188m 11s | Tests failed in hadoop-hdfs. |
| | | 251m 55s | |
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|| Reason || Tests ||
| Failed unit tests | hadoop.net.TestNetUtils |
| | hadoop.ha.TestZKFailoverController |
| | hadoop.hdfs.server.namenode.TestParallelImageWrite |
| | hadoop.hdfs.TestFileAppend2 |
| | hadoop.hdfs.server.namenode.snapshot.TestSnapshot |
| | hadoop.hdfs.server.namenode.ha.TestStandbyIsHot |
| | hadoop.hdfs.server.namenode.metrics.TestNameNodeMetrics |
| | hadoop.hdfs.TestDFSUpgradeFromImage |
| | hadoop.hdfs.TestDatanodeLayoutUpgrade |
| | hadoop.hdfs.server.namenode.ha.TestDNFencing |
| Timed out tests | org.apache.hadoop.cli.TestHDFSCLI |
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|| Subsystem || Report/Notes ||
| Patch URL |
http://issues.apache.org/jira/secure/attachment/12749223/HDFS-8859.001.patch |
| Optional Tests | javadoc javac unit findbugs checkstyle |
| git revision | trunk / b6265d3 |
| whitespace |
https://builds.apache.org/job/PreCommit-HDFS-Build/11934/artifact/patchprocess/whitespace.txt
|
| hadoop-common test log |
https://builds.apache.org/job/PreCommit-HDFS-Build/11934/artifact/patchprocess/testrun_hadoop-common.txt
|
| hadoop-hdfs test log |
https://builds.apache.org/job/PreCommit-HDFS-Build/11934/artifact/patchprocess/testrun_hadoop-hdfs.txt
|
| Test Results |
https://builds.apache.org/job/PreCommit-HDFS-Build/11934/testReport/ |
| Java | 1.7.0_55 |
| uname | Linux asf900.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/11934/console |
This message was automatically generated.
> Improve DataNode (ReplicaMap) memory footprint to save about 45%
> ----------------------------------------------------------------
>
> Key: HDFS-8859
> URL: https://issues.apache.org/jira/browse/HDFS-8859
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Yi Liu
> Assignee: Yi Liu
> Priority: Critical
> Attachments: HDFS-8859.001.patch
>
>
> By using following approach we can save about *45%* memory footprint for each
> block replica in DataNode memory (This JIRA only talks about *ReplicaMap* in
> DataNode), the details are:
> In ReplicaMap,
> {code}
> private final Map<String, Map<Long, ReplicaInfo>> map =
> new HashMap<String, Map<Long, ReplicaInfo>>();
> {code}
> Currently we use a HashMap {{Map<Long, ReplicaInfo>}} to store the replicas
> in memory. The key is block id of the block replica which is already
> included in {{ReplicaInfo}}, so this memory can be saved. Also HashMap Entry
> has a object overhead. We can implement a lightweight Set which is similar
> to {{LightWeightGSet}}, but not a fixed size ({{LightWeightGSet}} uses fix
> size for the entries array, usually it's a big value, an example is
> {{BlocksMap}}, this can avoid full gc since no need to resize), also we
> should be able to get Element through key.
> Following is comparison of memory footprint If we implement a lightweight set
> as described:
> We can save:
> {noformat}
> SIZE (bytes) ITEM
> 20 The Key: Long (12 bytes object overhead + 8
> bytes long)
> 12 HashMap Entry object overhead
> 4 reference to the key in Entry
> 4 reference to the value in Entry
> 4 hash in Entry
> {noformat}
> Total: -44 bytes
> We need to add:
> {noformat}
> SIZE (bytes) ITEM
> 4 a reference to next element in ReplicaInfo
> {noformat}
> Total: +4 bytes
> So totally we can save 40bytes for each block replica
> And currently one finalized replica needs around 46 bytes (notice: we ignore
> memory alignment here).
> We can save 1 - (4 + 46) / (44 + 46) = *45%* memory for each block replica
> in DataNode.
>
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