[ https://issues.apache.org/jira/browse/HDFS-8674?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Daryn Sharp updated HDFS-8674: ------------------------------ Attachment: HDFS-8674.trunk.patch fix conflicts on trunk stemming from under replicated now being low redundancy. > Improve performance of postponed block scans > -------------------------------------------- > > Key: HDFS-8674 > URL: https://issues.apache.org/jira/browse/HDFS-8674 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Affects Versions: 2.6.0 > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Priority: Critical > Attachments: HDFS-8674.2.patch, HDFS-8674.patch, HDFS-8674.patch, > HDFS-8674.trunk.patch > > > When a standby goes active, it marks all nodes as "stale" which will cause > block invalidations for over-replicated blocks to be queued until full block > reports are received from the nodes with the block. The replication monitor > scans the queue with O(N) runtime. It picks a random offset and iterates > through the set to randomize blocks scanned. > The result is devastating when a cluster loses multiple nodes during a > rolling upgrade. Re-replication occurs, the nodes come back, the excess block > invalidations are postponed. Rescanning just 2k blocks out of millions of > postponed blocks may take multiple seconds. During the scan, the write lock > is held which stalls all other processing. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org