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Kihwal Lee commented on HDFS-9178: ---------------------------------- +1 It looks like the only difference is in {{DataNodeFaultInjector}}. > Slow datanode I/O can cause a wrong node to be marked bad > --------------------------------------------------------- > > Key: HDFS-9178 > URL: https://issues.apache.org/jira/browse/HDFS-9178 > Project: Hadoop HDFS > Issue Type: Bug > Reporter: Kihwal Lee > Assignee: Kihwal Lee > Priority: Critical > Fix For: 2.7.2 > > Attachments: 002-HDFS-9178.branch-2.6.patch, > HDFS-9178.branch-2.6.patch, HDFS-9178.patch > > > When non-leaf datanode in a pipeline is slow on or stuck at disk I/O, the > downstream node can timeout on reading packet since even the heartbeat > packets will not be relayed down. > The packet read timeout is set in {{DataXceiver#run()}}: > {code} > peer.setReadTimeout(dnConf.socketTimeout); > {code} > When the downstream node times out and closes the connection to the upstream, > the upstream node's {{PacketResponder}} gets {{EOFException}} and it sends an > ack upstream with the downstream node status set to {{ERROR}}. This caused > the client to exclude the downstream node, even thought the upstream node was > the one got stuck. > The connection to downstream has longer timeout, so the downstream will > always timeout first. The downstream timeout is set in {{writeBlock()}} > {code} > int timeoutValue = dnConf.socketTimeout + > (HdfsConstants.READ_TIMEOUT_EXTENSION * targets.length); > int writeTimeout = dnConf.socketWriteTimeout + > (HdfsConstants.WRITE_TIMEOUT_EXTENSION * targets.length); > NetUtils.connect(mirrorSock, mirrorTarget, timeoutValue); > OutputStream unbufMirrorOut = NetUtils.getOutputStream(mirrorSock, > writeTimeout); > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)