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Todd Lipcon commented on HDFS-744: ---------------------------------- Looks pretty good! Just a few small things: - looks like hard tabs still snuck in one spot - I don't think hsync() needs to be synchronized: ie further writes could proceed to the stream while an earlier writer is waiting on a sync response ---- {code} // repeated hsyncs, not avoiding unnecessary sync here out.hsync(); checkSyncMetric(cluster, 2); {code} maybe add a note that says more explicitly something like: this is a potential future optimization that is not yet implemented, or something? > Support hsync in HDFS > --------------------- > > Key: HDFS-744 > URL: https://issues.apache.org/jira/browse/HDFS-744 > Project: Hadoop HDFS > Issue Type: New Feature > Components: data-node, hdfs client > Reporter: Hairong Kuang > Assignee: Lars Hofhansl > Attachments: HDFS-744-trunk-v2.patch, HDFS-744-trunk-v3.patch, > HDFS-744-trunk-v4.patch, HDFS-744-trunk-v5.patch, HDFS-744-trunk-v6.patch, > HDFS-744-trunk-v7.patch, HDFS-744-trunk.patch, hdfs-744-v2.txt, > hdfs-744-v3.txt, hdfs-744.txt > > > HDFS-731 implements hsync by default as hflush. As descriibed in HADOOP-6313, > the real expected semantics should be "flushes out to all replicas and all > replicas have done posix fsync equivalent - ie the OS has flushed it to the > disk device (but the disk may have it in its cache)." This jira aims to > implement the expected behaviour. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira