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Íñigo Goiri commented on HDFS-12288: ------------------------------------ Currently there is a metric called {{xceiverCount}} which returns the number of threads in a particular threadpool. We could have only one client connected to the Datanode but as we had 50 threads created at some point, we would claim that xceiverCount is 50. [~rushabh.shah], is your argument that we should leave it as is? Do you mind elaborating? > Fix DataNode's xceiver count calculation > ---------------------------------------- > > Key: HDFS-12288 > URL: https://issues.apache.org/jira/browse/HDFS-12288 > Project: Hadoop HDFS > Issue Type: Bug > Components: datanode, hdfs > Reporter: Lukas Majercak > Assignee: Lukas Majercak > Attachments: HDFS-12288.001.patch, HDFS-12288.002.patch > > > The problem with the ThreadGroup.activeCount() method is that the method is > only a very rough estimate, and in reality returns the total number of > threads in the thread group as opposed to the threads actually running. > In some DNs, we saw this to return 50~ for a long time, even though the > actual number of DataXceiver threads was next to none. > This is a big issue as we use the xceiverCount to make decisions on the NN > for choosing replication source DN or returning DNs to clients for R/W. > The plan is to reuse the DataNodeMetrics.dataNodeActiveXceiversCount value > which only accounts for actual number of DataXcevier threads currently > running and thus represents the load on the DN much better. -- 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