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https://issues.apache.org/jira/browse/HDFS-9239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15176926#comment-15176926
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Tsz Wo Nicholas Sze commented on HDFS-9239:
-------------------------------------------
This feature is going to be very useful for busy clusters.
Some quick comments:
{code}
// DatanodeManager.handleLifeline
synchronized (heartbeatManager) {
synchronized (datanodeMap) {
DatanodeDescriptor nodeinfo = getDatanode(nodeReg);
...
heartbeatManager.updateLifeline(nodeinfo, reports, cacheCapacity,
cacheUsed, xceiverCount, failedVolumes, volumeFailureSummary);
}
{code}
- synchronized (datanodeMap) shoud be synchronized (this). We no longer
synchronize on datanodeMap.
- Do we need synchronized (heartbeatManager)? heartbeatManager.updateLifeline
is already synchronized.
> DataNode Lifeline Protocol: an alternative protocol for reporting DataNode
> liveness
> -----------------------------------------------------------------------------------
>
> Key: HDFS-9239
> URL: https://issues.apache.org/jira/browse/HDFS-9239
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: datanode, namenode
> Reporter: Chris Nauroth
> Assignee: Chris Nauroth
> Attachments: DataNode-Lifeline-Protocol.pdf, HDFS-9239.001.patch,
> HDFS-9239.002.patch
>
>
> This issue proposes introduction of a new feature: the DataNode Lifeline
> Protocol. This is an RPC protocol that is responsible for reporting liveness
> and basic health information about a DataNode to a NameNode. Compared to the
> existing heartbeat messages, it is lightweight and not prone to resource
> contention problems that can harm accurate tracking of DataNode liveness
> currently. The attached design document contains more details.
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