[ https://issues.apache.org/jira/browse/HDFS-15610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17307589#comment-17307589 ]
Wei-Chiu Chuang commented on HDFS-15610: ---------------------------------------- I think this is a quite important improvement which stabilizes the upgrade experience. I'll cherry pick it to lower branches > Reduce datanode upgrade/hardlink thread > --------------------------------------- > > Key: HDFS-15610 > URL: https://issues.apache.org/jira/browse/HDFS-15610 > Project: Hadoop HDFS > Issue Type: Bug > Components: datanode > Affects Versions: 3.0.0, 3.1.4 > Reporter: Karthik Palanisamy > Assignee: Karthik Palanisamy > Priority: Major > Labels: pull-request-available > Fix For: 3.4.0 > > Time Spent: 1h 10m > Remaining Estimate: 0h > > There is a kernel overhead on datanode upgrade. If datanode with millions of > blocks and 10+ disks then block-layout migration will be super expensive > during its hardlink operation. Slowness is observed when running with large > hardlink threads(dfs.datanode.block.id.layout.upgrade.threads, default is 12 > thread for each disk) and its runs for 2+ hours. > I.e 10*12=120 threads (for 10 disks) > Small test: > RHEL7, 32 cores, 20 GB RAM, 8 GB DN heap > ||dfs.datanode.block.id.layout.upgrade.threads||Blocks||Disks||Time taken|| > |12|3.3 Million|1|2 minutes and 59 seconds| > |6|3.3 Million|1|2 minutes and 35 seconds| > |3|3.3 Million|1|2 minutes and 51 seconds| > Tried same test twice and 95% is accurate (only a few sec difference on each > iteration). Using 6 thread is faster than 12 thread because of its overhead. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org