[ https://issues.apache.org/jira/browse/HDFS-8674?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andrew Wang updated HDFS-8674: ------------------------------ Target Version/s: 2.8.0, 2.7.4, 3.0.0-alpha2 (was: 2.7.4) Added some more target versions for tracking. Seems like this would still be good to get in. > 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.patch, HDFS-8674.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