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https://issues.apache.org/jira/browse/HDFS-16044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17471308#comment-17471308
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Xiaoqiao He commented on HDFS-16044:
------------------------------------
Thanks [~ayushtkn] for your comments. This is valuable improvement, but it is
incompatible changes even at hadoop project scope only as you mentioned above.
We need rethink how to improve and be compatible. TBH, not any graceful way
now, any suggestions are welcome. Thanks.
> Fix getListing call getLocatedBlocks even source is a directory
> ---------------------------------------------------------------
>
> Key: HDFS-16044
> URL: https://issues.apache.org/jira/browse/HDFS-16044
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Reporter: ludun
> Assignee: ludun
> Priority: Major
> Attachments: HDFS-16044.00.patch, HDFS-16044.01.patch,
> HDFS-16044.02.patch, HDFS-16044.03.patch, HDFS-16044.05.patch
>
>
> In production cluster when call getListing very frequent. The processing
> time of rpc request is very high. we try to optimize the performance of
> getListing request.
> After some check, we found that, even the source and child is dir, the
> getListing request also call getLocatedBlocks.
> the request is and needLocation is false
> {code:java}
> 2021-05-27 15:16:07,093 TRACE ipc.ProtobufRpcEngine: 1: Call ->
> 8-5-231-4/8.5.231.4:25000: getListing {src:
> "/data/connector/test/topics/102test" startAfter: "" needLocation: false}
> {code}
> but getListing request 1000 times getLocatedBlocks which not needed.
> {code:java}
> `---ts=2021-05-27 14:19:15;thread_name=IPC Server handler 86 on
> 25000;id=e6;is_daemon=true;priority=5;TCCL=sun.misc.Launcher$AppClassLoader@5fcfe4b2
> `---[35.068532ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirStatAndListingOp:getListing()
> +---[0.003542ms]
> org.apache.hadoop.hdfs.server.namenode.INodesInPath:getPathComponents() #214
> +---[0.003053ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirectory:isExactReservedName() #95
> +---[0.002938ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirectory:readLock() #218
> +---[0.00252ms]
> org.apache.hadoop.hdfs.server.namenode.INodesInPath:isDotSnapshotDir() #220
> +---[0.002788ms]
> org.apache.hadoop.hdfs.server.namenode.INodesInPath:getPathSnapshotId() #223
> +---[0.002905ms]
> org.apache.hadoop.hdfs.server.namenode.INodesInPath:getLastINode() #224
> +---[0.002785ms]
> org.apache.hadoop.hdfs.server.namenode.INode:getStoragePolicyID() #230
> +---[0.002236ms]
> org.apache.hadoop.hdfs.server.namenode.INode:isDirectory() #233
> +---[0.002919ms]
> org.apache.hadoop.hdfs.server.namenode.INode:asDirectory() #242
> +---[0.003408ms]
> org.apache.hadoop.hdfs.server.namenode.INodeDirectory:getChildrenList() #243
> +---[0.005942ms]
> org.apache.hadoop.hdfs.server.namenode.INodeDirectory:nextChild() #244
> +---[0.002467ms] org.apache.hadoop.hdfs.util.ReadOnlyList:size() #245
> +---[0.005481ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirectory:getLsLimit() #247
> +---[0.002176ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirectory:getLsLimit() #248
> +---[min=0.00211ms,max=0.005157ms,total=2.247572ms,count=1000]
> org.apache.hadoop.hdfs.util.ReadOnlyList:get() #252
> +---[min=0.001946ms,max=0.005411ms,total=2.041715ms,count=1000]
> org.apache.hadoop.hdfs.server.namenode.INode:isSymlink() #253
> +---[min=0.002176ms,max=0.005426ms,total=2.264472ms,count=1000]
> org.apache.hadoop.hdfs.server.namenode.INode:getLocalStoragePolicyID() #254
> +---[min=0.002251ms,max=0.006849ms,total=2.351935ms,count=1000]
> org.apache.hadoop.hdfs.server.namenode.FSDirStatAndListingOp:getStoragePolicyID()
> #95
> +---[min=0.006091ms,max=0.012333ms,total=6.439434ms,count=1000]
> org.apache.hadoop.hdfs.server.namenode.FSDirStatAndListingOp:createFileStatus()
> #257
> +---[min=0.00269ms,max=0.004995ms,total=2.788194ms,count=1000]
> org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus:getLocatedBlocks() #265
> +---[0.003234ms]
> org.apache.hadoop.hdfs.protocol.DirectoryListing:<init>() #274
> `---[0.002457ms]
> org.apache.hadoop.hdfs.server.namenode.FSDirectory:readUnlock() #277
> {code}
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