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https://issues.apache.org/jira/browse/HADOOP-5632?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12717086#action_12717086
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Khaled Elmeleegy commented on HADOOP-5632:
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To test the scalability of the patch, i.e. whether the patched JT will be able
to keep up with the load in a large cluster or not, I've used ~200 nodes
cluster. Each node has two quad core CPUs, 16GB of memory, and 4 disks. On each
node, I ran 10 TaskTrackers, simulating ~2000 node cluster. Each TT has 6 map
slots and 2 reduce slots. I patched the hadoop trunk with the 5632 patch. I ran
the sleep job from the examples jar with 500,000 maps and map runtime (sleep
time) of 20 seconds. I measured the slot utilization and it was 99.8%. I
followed the CPU utilization at the jobtracker and all the 8 cpus were like 20%
busy on average. Jobtracker's CPU utilization varies along time, but the CPUs
are no where near saturation. Also, I didn't observe lock contention, i.e. Load
was, more or less, evenly balanced among all the CPUs.
I cranked up the load to stress test the JT by reducing the map runtime (sleep
time) to 1 second. Still, the JT was able to keep up with the load with no
problem.
> Jobtracker leaves tasktrackers underutilized
> --------------------------------------------
>
> Key: HADOOP-5632
> URL: https://issues.apache.org/jira/browse/HADOOP-5632
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Affects Versions: 0.18.0, 0.18.1, 0.18.2, 0.18.3, 0.19.0, 0.19.1, 0.20.0
> Environment: 2x HT 2.8GHz Intel Xeon, 3GB RAM, 4x 250GB HD linux
> boxes, 100 node cluster
> Reporter: Khaled Elmeleegy
> Attachments: hadoop-khaled-tasktracker.10s.uncompress.timeline.pdf,
> hadoop-khaled-tasktracker.150ms.uncompress.timeline.pdf, jobtracker.patch,
> jobtracker20.patch
>
>
> For some workloads, the jobtracker doesn't keep all the slots utilized even
> under heavy load.
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