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https://issues.apache.org/jira/browse/HDFS-8884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14707352#comment-14707352
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Hudson commented on HDFS-8884:
------------------------------
FAILURE: Integrated in Hadoop-Yarn-trunk #1024 (See
[https://builds.apache.org/job/Hadoop-Yarn-trunk/1024/])
HDFS-8884. Fail-fast check in BlockPlacementPolicyDefault#chooseTarget. (yliu)
(yliu: rev 80a29906bcd718bbba223fa099e523281d9f3369)
*
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDefaultBlockPlacementPolicy.java
* hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyDefault.java
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockPlacementPolicyWithNodeGroup.java
> Fail-fast check in BlockPlacementPolicyDefault#chooseTarget
> -----------------------------------------------------------
>
> Key: HDFS-8884
> URL: https://issues.apache.org/jira/browse/HDFS-8884
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Yi Liu
> Assignee: Yi Liu
> Fix For: 2.8.0
>
> Attachments: HDFS-8884.001.patch, HDFS-8884.002.patch
>
>
> In current BlockPlacementPolicyDefault, when choosing datanode storage to
> place block, we have following logic:
> {code}
> final DatanodeStorageInfo[] storages = DFSUtil.shuffle(
> chosenNode.getStorageInfos());
> int i = 0;
> boolean search = true;
> for (Iterator<Map.Entry<StorageType, Integer>> iter = storageTypes
> .entrySet().iterator(); search && iter.hasNext(); ) {
> Map.Entry<StorageType, Integer> entry = iter.next();
> for (i = 0; i < storages.length; i++) {
> StorageType type = entry.getKey();
> final int newExcludedNodes = addIfIsGoodTarget(storages[i],
> {code}
> We will iterate (actually two {{for}}, although they are usually small value)
> all storages of the candidate datanode even the datanode itself is not good
> (e.g. decommissioned, stale, too busy..), since currently we do all the check
> in {{addIfIsGoodTarget}}.
> We can fail-fast: check the datanode related conditions first, if the
> datanode is not good, then no need to shuffle and iterate the storages. Then
> it's more efficient.
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