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From "Alejandro Abdelnur (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-1021) Yarn Scheduler Load Simulator
Date Thu, 19 Sep 2013 15:52:53 GMT

    [ https://issues.apache.org/jira/browse/YARN-1021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13771988#comment-13771988

Alejandro Abdelnur commented on YARN-1021:

Thanks [~ywskycn], last set of NITs I believe:

* I still see the issue that the simulator is taking the fs.defaultFS from the hadoop conf
instead the one set to file:/// 
* The NM simulator initialization is much faster now, still it takes it time to get all NM
simulators running. We should print some kind of feedback to the terminal while this is happening,
something like every 5 seconds "N of M NMs initialized"
* The documentation should mention the default port of the simulator console, 10001
* The slsrun.sh script should not reset HADOOP_OPTS (this is handy to increase heap or configure
to connect a remote debugger/profiler)

> Yarn Scheduler Load Simulator
> -----------------------------
>                 Key: YARN-1021
>                 URL: https://issues.apache.org/jira/browse/YARN-1021
>             Project: Hadoop YARN
>          Issue Type: New Feature
>          Components: scheduler
>            Reporter: Wei Yan
>            Assignee: Wei Yan
>         Attachments: YARN-1021-demo.tar.gz, YARN-1021-images.tar.gz, YARN-1021.patch,
YARN-1021.patch, YARN-1021.patch, YARN-1021.patch, YARN-1021.patch, YARN-1021.patch, YARN-1021.patch,
YARN-1021.patch, YARN-1021.patch, YARN-1021.patch, YARN-1021.patch, YARN-1021.pdf
> The Yarn Scheduler is a fertile area of interest with different implementations, e.g.,
Fifo, Capacity and Fair  schedulers. Meanwhile, several optimizations are also made to improve
scheduler performance for different scenarios and workload. Each scheduler algorithm has its
own set of features, and drives scheduling decisions by many factors, such as fairness, capacity
guarantee, resource availability, etc. It is very important to evaluate a scheduler algorithm
very well before we deploy it in a production cluster. Unfortunately, currently it is non-trivial
to evaluate a scheduling algorithm. Evaluating in a real cluster is always time and cost consuming,
and it is also very hard to find a large-enough cluster. Hence, a simulator which can predict
how well a scheduler algorithm for some specific workload would be quite useful.
> We want to build a Scheduler Load Simulator to simulate large-scale Yarn clusters and
application loads in a single machine. This would be invaluable in furthering Yarn by providing
a tool for researchers and developers to prototype new scheduler features and predict their
behavior and performance with reasonable amount of confidence, there-by aiding rapid innovation.
> The simulator will exercise the real Yarn ResourceManager removing the network factor
by simulating NodeManagers and ApplicationMasters via handling and dispatching NM/AMs heartbeat
events from within the same JVM.
> To keep tracking of scheduler behavior and performance, a scheduler wrapper will wrap
the real scheduler.
> The simulator will produce real time metrics while executing, including:
> * Resource usages for whole cluster and each queue, which can be utilized to configure
cluster and queue's capacity.
> * The detailed application execution trace (recorded in relation to simulated time),
which can be analyzed to understand/validate the  scheduler behavior (individual jobs turn
around time, throughput, fairness, capacity guarantee, etc).
> * Several key metrics of scheduler algorithm, such as time cost of each scheduler operation
(allocate, handle, etc), which can be utilized by Hadoop developers to find the code spots
and scalability limits.
> The simulator will provide real time charts showing the behavior of the scheduler and
its performance.
> A short demo is available http://www.youtube.com/watch?v=6thLi8q0qLE, showing how to
use simulator to simulate Fair Scheduler and Capacity Scheduler.

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