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Gopal V commented on HDFS-8315: ------------------------------- [~kihwal]: the HDFS in-memory layer is IOPS bound on logging stream - because log4j uses a single sync block around each appender to maintain ordering of logs. I was under the impression that you can always turn on DEBUG logging for a ClientTraceLog using {{hadoop daemonlog}} command? > Datanode does not log reads > --------------------------- > > Key: HDFS-8315 > URL: https://issues.apache.org/jira/browse/HDFS-8315 > Project: Hadoop HDFS > Issue Type: Bug > Reporter: Kihwal Lee > Assignee: Kihwal Lee > Priority: Critical > Attachments: HDFS-8315.patch > > > HDFS-6836 made datanode read request logging DEBUG. There is a good reason > why it was at INFO for so many years. This is very useful in debugging load > issues. This jira will revert HDFS-6836. > We haven't seen it being a bottleneck on busy hbase clusters, but if someone > thinks it is a serious overhead, please make it configurable in a separate > jira. -- This message was sent by Atlassian JIRA (v6.3.4#6332)