Varys

Varys is an open-source application-aware network scheduler that aims to improve communication performance of Big Data applications. Its target applications/jobs include those written in Spark, Hadoop, YARN, BSP, and similar data-parallel frameworks.

Varys provides a simple API that allows data-parallel frameworks to express their communication requirements as coflows with minimal changes to the framework. User jobs do not require any modification. Using coflows as the basic abstraction of network scheduling, Varys implements novel schedulers either to make applications faster or to make time-restricted applications complete within deadlines.

To learn more, visit http://varys.net/

Building Varys

Varys is built on Scala 2.10.4. To build Varys and example programs using it, run

./sbt/sbt package

Dependency Information

Currently, Varys has not yet been published to any repository. The easiest way to use it in your project is to first publish it to local ivy repository.

./sbt/sbt publish-local

Other projects on the same machine can then list the project as a dependency.

SBT

libraryDependencies += "net.varys" %% "varys-core" % "0.2.0-SNAPSHOT"

Apache Maven

<dependency>
  <groupId>net.varys</groupId>
  <artifactId>varys-core</artifactId>
  <version>0.2.0-SNAPSHOT</version>
</dependency>

Apache Ant

<dependency org="net.varys" name="varys-core" rev="0.2.0-SNAPSHOT">
  <artifact name="varys-core" type="jar" />
</dependency>

Directly putting the jar in your classpath should also work. It is located at ./core/target/scala-*/varys-core*.jar.

Example Programs

Varys also comes with several sample programs in the examples directory. For example, the SenderClient* and their counterparts ReceiverClient* programs show how to use coflows on different data sources like disk or memory.

To run any pair of them (e.g., one creating random coflows) in your local machine, first start Varys by typing

./bin/start-all.sh

Now, go to http://localhost:16016 in your browser to find the MASTER_URL.

Next, start the sender and the receiver

./run varys.examples.SenderClientFake <MASTER_URL>
./run varys.examples.ReceiverClientFake <MASTER_URL> COFLOW-000000

This should log statements on the console stating coflow register, transfer, and other events.

Finally, stop Varys by typing

./bin/stop-all.sh

While these examples by themselves do not perform any task, they show how a framework might use them (e.g., a mapper being the sender and reducer being the receiver in MapReduce). Note that, we are manually providing the CoflowId (COFLOW-000000) to the reciever, which should be provided by the framework driver (e.g., JobTracker for Hadoop or SparkContext for Spark).

Take a look at the BroadcastService example that does a slightly better job in containing everything (driver, sender, and receiver) in the same application.