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Wei-Chiu Chuang commented on HDFS-12136: ---------------------------------------- HDFS-6804 is another facet of the same race condition. [~brahmareddy] made a unit test that reliably reproduces the bug if HDFS-11160 is reverted. > BlockSender performance regression due to volume scanner edge case > ------------------------------------------------------------------ > > Key: HDFS-12136 > URL: https://issues.apache.org/jira/browse/HDFS-12136 > Project: Hadoop HDFS > Issue Type: Improvement > Components: datanode > Affects Versions: 2.8.0 > Reporter: Daryn Sharp > Assignee: Daryn Sharp > Priority: Critical > Attachments: HDFS-12136.branch-2.patch, HDFS-12136.trunk.patch > > > HDFS-11160 attempted to fix a volume scan race for a file appended mid-scan > by reading the last checksum of finalized blocks within the {{BlockSender}} > ctor. Unfortunately it's holding the exclusive dataset lock to open and read > the metafile multiple times Block sender instantiation becomes serialized. > Performance completely collapses under heavy disk i/o utilization or high > xceiver activity. Ex. lost node replication, balancing, or decommissioning. > The xceiver threads congest creating block senders and impair the heartbeat > processing that is contending for the same lock. Combined with other lock > contention issues, pipelines break and nodes sporadically go dead. -- 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