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https://issues.apache.org/jira/browse/HDFS-7495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14238590#comment-14238590
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Ted Yu commented on HDFS-7495:
------------------------------

Here is one path where lock on this is not obtained first:
read() -> pread() -> hedgedFetchBlockByteRange() -> chooseDataNode() -> 
getBlockAt()

> Lock inversion in DFSInputStream#getBlockAt()
> ---------------------------------------------
>
>                 Key: HDFS-7495
>                 URL: https://issues.apache.org/jira/browse/HDFS-7495
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Priority: Minor
>
> There're two locks: one on DFSInputStream.this , one on 
> DFSInputStream.infoLock
> Normally lock is obtained on infoLock, then on DFSInputStream.infoLock
> However, such order is not observed in DFSInputStream#getBlockAt() :
> {code}
>     synchronized(infoLock) {
> ...
>       if (updatePosition) {
>         // synchronized not strictly needed, since we only get here
>         // from synchronized caller methods
>         synchronized(this) {
> {code}



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