JiankunLiu created YARN-2381:
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Summary: CLONE - Yarn Scheduler Load Simulator
Key: YARN-2381
URL: https://issues.apache.org/jira/browse/YARN-2381
Project: Hadoop YARN
Issue Type: New Feature
Components: scheduler
Reporter: JiankunLiu
Assignee: Wei Yan
Fix For: 2.3.0
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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