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Zhaohui Xin edited comment on MAPREDUCE-7100 at 2/3/19 8:26 AM: ---------------------------------------------------------------- Hi, I added a patch to cancel locality resource request as an option in job. In my opinion, canceling local requests will also avoid rack resolution issues. was (Author: uranus): Hi, I added a patch to cancel locality resource request as an option in job. > Provide options to skip adding resource request for data-local and rack-local > respectively > ------------------------------------------------------------------------------------------ > > Key: MAPREDUCE-7100 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-7100 > Project: Hadoop Map/Reduce > Issue Type: Improvement > Components: applicationmaster > Reporter: Xiang Li > Assignee: Zhaohui Xin > Priority: Critical > Attachments: MAPREDUCE-7100.001.patch > > > We are using hadoop 2.7.3 and the computing layer is running out of the > storage cluster (that is, node managers are running on a different set of > nodes from data nodes). The problem we meet is that the container allocation > is quite slow for some jobs. > After some debugging, we found that in > org.apache.hadoop.mapreduce.v2.app.rm.RMContainerRequestor#addContainerReq() > (the following code is from trunk, not 2.7.3) > {code} > protected void addContainerReq(ContainerRequest req) { > // Create resource requests > for (String host : req.hosts) { > // Data-local > if (!isNodeBlacklisted(host)) { > addResourceRequest(req.priority, host, req.capability, > null); > } > } > // Nothing Rack-local for now > for (String rack : req.racks) { > addResourceRequest(req.priority, rack, req.capability, > null); > } > // Off-switch > addResourceRequest(req.priority, ResourceRequest.ANY, req.capability, > req.nodeLabelExpression); > } > {code} > It seem that the request of data-local and rack-local could be skipped when > computing layer is not the same as the storage cluster. > If I get it correctly, req.hosts and req.racks are provided by InputFormat. > If the mapper is to read HDFS, req.hosts is the corresponding data node and > req.racks is its rack. The debug log of AM is like: > {code} > org.apache.hadoop.mapreduce.v2.app.rm.RMContainerRequestor: > addResourceRequest: applicationId=1 priority=20 resourceName=<data-node> > numContainers=1 #asks=1 > org.apache.hadoop.mapreduce.v2.app.rm.RMContainerRequestor: > addResourceRequest: applicationId=1 priority=20 resourceName=<its rack> > numContainers=1 #asks=2 > org.apache.hadoop.mapreduce.v2.app.rm.RMContainerRequestor: > addResourceRequest: applicationId=1 priority=20 resourceName=* > numContainers=1 #asks=3 > {code} > Although eventually, the resource request with resourceName=<data-node> will > not be satisfied (because the data node is not node manager) in RM, it could > be better if AM does not request data-local or rack-local at the very > beginning, when we already know that computer layer runs out of the storage > cluster. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: mapreduce-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: mapreduce-issues-h...@hadoop.apache.org