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Chao Sun commented on HDFS-10702: --------------------------------- Thanks [~clouderajiayi] and [~mackrorysd] for this great work! we are experiencing lots of NN issues at Uber and this could be a big help. [~mingma] and [~zhz]: you have raised the question of potential race conditions with {{cpLock}}. However, I'm not sure if this is possible: to my understanding the {{cpLock}} is used to protect edit log from checkpointing and the tailer, which the read operations would not need to touch (seems like). Please correct me if I'm wrong. :) > Add a Client API and Proxy Provider to enable stale read from Standby > --------------------------------------------------------------------- > > Key: HDFS-10702 > URL: https://issues.apache.org/jira/browse/HDFS-10702 > Project: Hadoop HDFS > Issue Type: New Feature > Reporter: Jiayi Zhou > Assignee: Sean Mackrory > Priority: Minor > Attachments: HDFS-10702.001.patch, HDFS-10702.002.patch, > HDFS-10702.003.patch, HDFS-10702.004.patch, HDFS-10702.005.patch, > HDFS-10702.006.patch, HDFS-10702.007.patch, HDFS-10702.008.patch, > StaleReadfromStandbyNN.pdf > > > Currently, clients must always talk to the active NameNode when performing > any metadata operation, which means active NameNode could be a bottleneck for > scalability. One way to solve this problem is to send read-only operations to > Standby NameNode. The disadvantage is that it might be a stale read. > Here, I'm thinking of adding a Client API to enable/disable stale read from > Standby which gives Client the power to set the staleness restriction. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org