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https://issues.apache.org/jira/browse/HDFS-12130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16088051#comment-16088051
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Hudson commented on HDFS-12130:
-------------------------------
SUCCESS: Integrated in Jenkins build Hadoop-trunk-Commit #12009 (See
[https://builds.apache.org/job/Hadoop-trunk-Commit/12009/])
HDFS-12130. Optimizing permission check for getContentSummary. (szetszwo: rev
a29fe100b3c671954b759add5923a2b44af9e6a4)
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/Snapshot.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeDirectory.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ContentSummaryComputationContext.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectorySnapshottableFeature.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockCollection.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/DirectoryWithQuotaFeature.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/DirectoryWithSnapshotFeature.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSPermissionChecker.java
* (edit)
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeReference.java
* (add)
hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestGetContentSummaryWithPermission.java
> Optimizing permission check for getContentSummary
> -------------------------------------------------
>
> Key: HDFS-12130
> URL: https://issues.apache.org/jira/browse/HDFS-12130
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Chen Liang
> Assignee: Chen Liang
> Fix For: 2.9.0, 3.0.0-beta1
>
> Attachments: HDFS-12130.001.patch, HDFS-12130.002.patch,
> HDFS-12130.003.patch
>
>
> Currently, {{getContentSummary}} takes two phases to complete:
> - phase1. check the permission of the entire subtree. If any subdirectory
> does not have {{READ_EXECUTE}}, an access control exception is thrown and
> {{getContentSummary}} terminates here (unless it's super user).
> - phase2. If phase1 passed, it will then traverse the entire tree recursively
> to get the actual content summary.
> An issue is, both phases currently hold the fs lock.
> Phase 2 has already been written that, it will yield the fs lock over time,
> such that it does not block other operations for too long. However phase 1
> does not yield. Meaning it's possible that the permission check phase still
> blocks things for long time.
> One fix is to add lock yield to phase 1. But a simpler fix is to merge phase
> 1 into phase 2. Namely, instead of doing a full traversal for permission
> check first, we start with phase 2 directly, but for each directory, before
> obtaining its summary, check its permission first. This way we take advantage
> of existing lock yield in phase 2 code and still able to check permission and
> terminate on access exception.
> Thanks [~szetszwo] for the offline discussions!
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