[jira] Commented: (MAPREDUCE-1764) FairScheduler locality delay may put heavy pressure on Jobtracker
[ https://issues.apache.org/jira/browse/MAPREDUCE-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12867424#action_12867424 ] Joydeep Sen Sarma commented on MAPREDUCE-1764: -- it seems better to find out why the index is not helping (assuming it's actually being used) rather than adding another cache on top .. > FairScheduler locality delay may put heavy pressure on Jobtracker > - > > Key: MAPREDUCE-1764 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1764 > Project: Hadoop Map/Reduce > Issue Type: Bug >Affects Versions: 0.22.0 >Reporter: Scott Chen >Assignee: Dmytro Molkov > Fix For: 0.22.0 > > > FairScheduler locality delay feature holds the scheduling of jobs until it > gets good locality. > This greatly improves the locality of the tasks. Reduce the cost of traffic. > We have observed the following problem on FairScheduler locality delay: > We have some machines have older data and some newly added machines do not > have important data. > When these machines send heartbeat, JT scans tasks to find jobs has the right > locality. > Often time, these machines will scan all of the tasks of all the jobs and do > not get any tasks. > Scanning all the tasks on the JT is very costly. This makes JT very slow. > And these machines often time do not get scheduled. This hurts the cluster > utilization. > Any ideas? -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
[jira] Commented: (MAPREDUCE-1764) FairScheduler locality delay may put heavy pressure on Jobtracker
[ https://issues.apache.org/jira/browse/MAPREDUCE-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12867300#action_12867300 ] Scott Chen commented on MAPREDUCE-1764: --- Joydeep: Matei and I had some discussion and we have also looked the code. In JobInProgress, there is such a HashMap of node->[tasks] and rack->[tasks] exists. It is not clear to me why this is so slow. I agree with your point that we should not leave the slots idle especially in the case that cluster is full of jobs. > FairScheduler locality delay may put heavy pressure on Jobtracker > - > > Key: MAPREDUCE-1764 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1764 > Project: Hadoop Map/Reduce > Issue Type: Bug >Affects Versions: 0.22.0 >Reporter: Scott Chen >Assignee: Dmytro Molkov > Fix For: 0.22.0 > > > FairScheduler locality delay feature holds the scheduling of jobs until it > gets good locality. > This greatly improves the locality of the tasks. Reduce the cost of traffic. > We have observed the following problem on FairScheduler locality delay: > We have some machines have older data and some newly added machines do not > have important data. > When these machines send heartbeat, JT scans tasks to find jobs has the right > locality. > Often time, these machines will scan all of the tasks of all the jobs and do > not get any tasks. > Scanning all the tasks on the JT is very costly. This makes JT very slow. > And these machines often time do not get scheduled. This hurts the cluster > utilization. > Any ideas? -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
[jira] Commented: (MAPREDUCE-1764) FairScheduler locality delay may put heavy pressure on Jobtracker
[ https://issues.apache.org/jira/browse/MAPREDUCE-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12866389#action_12866389 ] Joydeep Sen Sarma commented on MAPREDUCE-1764: -- how expensive (memory wise) would it be to add indices from node->[tasks] and rack->[tasks] based on split information? leaving slots idle seems like a real bummer. it would seem better to be greedy and always grab something (especially if the fraction of non-local tasks is within tolerable limits) > FairScheduler locality delay may put heavy pressure on Jobtracker > - > > Key: MAPREDUCE-1764 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1764 > Project: Hadoop Map/Reduce > Issue Type: Bug >Affects Versions: 0.22.0 >Reporter: Scott Chen >Assignee: Dmytro Molkov > Fix For: 0.22.0 > > > FairScheduler locality delay feature holds the scheduling of jobs until it > gets good locality. > This greatly improves the locality of the tasks. Reduce the cost of traffic. > We have observed the following problem on FairScheduler locality delay: > We have some machines have older data and some newly added machines do not > have important data. > When these machines send heartbeat, JT scans tasks to find jobs has the right > locality. > Often time, these machines will scan all of the tasks of all the jobs and do > not get any tasks. > Scanning all the tasks on the JT is very costly. This makes JT very slow. > And these machines often time do not get scheduled. This hurts the cluster > utilization. > Any ideas? -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
[jira] Commented: (MAPREDUCE-1764) FairScheduler locality delay may put heavy pressure on Jobtracker
[ https://issues.apache.org/jira/browse/MAPREDUCE-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12866336#action_12866336 ] Scott Chen commented on MAPREDUCE-1764: --- One option is to cache the searched result for each TT. So next time we directly skip the TT without the allowed locality level. What do you think? > FairScheduler locality delay may put heavy pressure on Jobtracker > - > > Key: MAPREDUCE-1764 > URL: https://issues.apache.org/jira/browse/MAPREDUCE-1764 > Project: Hadoop Map/Reduce > Issue Type: Bug >Affects Versions: 0.22.0 >Reporter: Scott Chen >Assignee: Dmytro Molkov > Fix For: 0.22.0 > > > FairScheduler locality delay feature holds the scheduling of jobs until it > gets good locality. > This greatly improves the locality of the tasks. Reduce the cost of traffic. > We have observed the following problem on FairScheduler locality delay: > We have some machines have older data and some newly added machines do not > have important data. > When these machines send heartbeat, JT scans tasks to find jobs has the right > locality. > Often time, these machines will scan all of the tasks of all the jobs and do > not get any tasks. > Scanning all the tasks on the JT is very costly. This makes JT very slow. > And these machines often time do not get scheduled. This hurts the cluster > utilization. > Any ideas? -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.