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Colin Patrick McCabe commented on HDFS-6735: -------------------------------------------- Thanks, Steve. And thanks Stack and Liang, for bearing with me on this one :) Looking forward to figuring this out. > A minor optimization to avoid pread() be blocked by read() inside the same > DFSInputStream > ----------------------------------------------------------------------------------------- > > Key: HDFS-6735 > URL: https://issues.apache.org/jira/browse/HDFS-6735 > Project: Hadoop HDFS > Issue Type: Improvement > Components: hdfs-client > Affects Versions: 3.0.0 > Reporter: Liang Xie > Assignee: Liang Xie > Attachments: HDFS-6735-v2.txt, HDFS-6735.txt > > > In current DFSInputStream impl, there're a couple of coarser-grained locks in > read/pread path, and it has became a HBase read latency pain point so far. In > HDFS-6698, i made a minor patch against the first encourtered lock, around > getFileLength, in deed, after reading code and testing, it shows still other > locks we could improve. > In this jira, i'll make a patch against other locks, and a simple test case > to show the issue and the improved result. > This is important for HBase application, since in current HFile read path, we > issue all read()/pread() requests in the same DFSInputStream for one HFile. > (Multi streams solution is another story i had a plan to do, but probably > will take more time than i expected) -- This message was sent by Atlassian JIRA (v6.2#6252)