[ https://issues.apache.org/jira/browse/HDFS-14111?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wei-Chiu Chuang reassigned HDFS-14111: -------------------------------------- Assignee: Sahil Takiar > hdfsOpenFile on HDFS causes unnecessary IO from file offset 0 > ------------------------------------------------------------- > > Key: HDFS-14111 > URL: https://issues.apache.org/jira/browse/HDFS-14111 > Project: Hadoop HDFS > Issue Type: Bug > Components: hdfs-client, libhdfs > Affects Versions: 3.2.0 > Reporter: Todd Lipcon > Assignee: Sahil Takiar > Priority: Major > > hdfsOpenFile() calls readDirect() with a 0-length argument in order to check > whether the underlying stream supports bytebuffer reads. With DFSInputStream, > the read(0) isn't short circuited, and results in the DFSClient opening a > block reader. In the case of a remote block, the block reader will actually > issue a read of the whole block, causing the datanode to perform unnecessary > IO and network transfers in order to fill up the client's TCP buffers. This > causes performance degradation. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org