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https://issues.apache.org/jira/browse/YARN-1021?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14952216#comment-14952216
 ] 

YukunTsang commented on YARN-1021:
----------------------------------

Hey Wei Yan, I tried to run this simulator on my YARN cluster, but some problem 
occured when I am running the simulator using command "bin/slsrun.sh 
--input-rumen=sample-data/2jobs2min-rumen-jh.json --output-dir=output/"

The logs I get from the cmd are as follows:
Exception in thread "main" java.lang.RuntimeException: 
java.lang.NullPointerException
        at 
org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:134)
        at 
org.apache.hadoop.yarn.sls.SLSRunner.startAMFromRumenTraces(SLSRunner.java:398)
        at org.apache.hadoop.yarn.sls.SLSRunner.startAM(SLSRunner.java:250)
        at org.apache.hadoop.yarn.sls.SLSRunner.start(SLSRunner.java:145)
        at org.apache.hadoop.yarn.sls.SLSRunner.main(SLSRunner.java:528)
Caused by: java.lang.NullPointerException
        at 
java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936)
        at 
org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:126)
        ... 4 more

What should I do to get rid of this problem?
P.S. I used the default configuration file

> 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
>             Fix For: 2.3.0
>
>         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.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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