Project: Beam (App Definition and Development / Streaming & Messaging)
File: nemo.md

type: runners title: "Apache Nemo Runner" aliases: /learn/runners/nemo/ <!-- Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> The Apache Nemo Runner can be used to execute Beam pipelines using . The Nemo Runner can optimize Beam pipelines with the Nemo compiler through various optimization passes and execute them in a distributed fashion using the Nemo runtime. You can also deploy a self-contained application for local mode or run using resource managers like YARN or Mesos. The Nemo Runner executes Beam pipelines on top of Apache Nemo, providing: Batch and streaming pipelines Fault-tolerance Integration with YARN and other components of the Apache Hadoop ecosystem Support for the various optimizations provided by the Nemo optimizer The documents the supported capabilities of the Nemo Runner. The Nemo Runner can be used simply by adding a dependency on a version of the Nemo runner newer than `0.1` to your pom.xml as follows: ``` <dependency> <groupId>org.apache.nemo</groupId> <artifactId>nemo-compiler-frontend-beam</artifactId> <version>${nemo.version}</version> </dependency> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>${hadoop.version}</version> <exclusions> <exclusion> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> </exclusion> <exclusion> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> </exclusion> </exclusions> </dependency> ``` A self-contained application might be easier to manage and allows you to fully use the functionality that Nemo provides. Simply add the dependency shown above and shade the application JAR using the Maven Shade plugin: ``` <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <configuration> <createDependencyReducedPom>false</createDependencyReducedPom> <filters> <filter> <artifact>:</artifact> <excludes> <exclude>META-INF/*.SF</exclude> <exclude>META-INF/*.DSA</exclude> <exclude>META-INF/*.RSA</exclude> </excludes> </filter> </filters> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <shadedArtifactAttached>true</shadedArtifactAttached> <shadedClassifierName>shaded</shadedClassifierName> <transformers> <transformer

</transformers> </configuration> </execution> </executions> </plugin> ``` After running `mvn package`, run `ls target` and you should see the following output (in this example, your artifactId is `beam-examples` and the version is `1.0.0`): ``` beam-examples-1.0.0-shaded.jar ``` With this shaded jar, you can use the `bin/run_beam.sh` shell script as follows: ``` ./bin/run_beam.sh \ -jobid mrdefault \ -user_main org.apache.nemo.examples.beam.WordCount \ -userargs "`pwd`/examples/resources/testinputwordcount `pwd`/examples/resources/testoutput_wordcount" ``` To use Nemo using YARN, set the `-deploy_mode` flag on Nemo to `yarn`. More instructions can be seen on the README of the . When executing your pipeline with the Nemo Runner, you should consider the following pipeline options: | Field | Description | Default Value | | - || --:| | `runner` | The pipeline runner to use. This option allows you to determine the pipeline runner at runtime. | Set to `NemoRunner` to run using Nemo. | | `maxBundleSize` | The maximum number of elements in a bundle. | 1000 | | `maxBundleTimeMillis` | The maximum time to wait before finalizing a bundle (in milliseconds). | 1000 | More options are to be added to the list, to fully support the various options that Nemo supports. When submitting a Nemo application to the cluster, it is common to use the `bin/run_beam.sh` script that is provided within the Nemo installation. The script also provides a richer set of options that you can pass on to configure various actions of Nemo. Please refer to the for more information. You can monitor a running Nemo job using the Nemo WebUI. The docs are currently being updated, but more information can be found on the . Add the options `-schedulerimplclass_name org.apache.nemo.runtime.master.scheduler.StreamingScheduler` and `-optimization_policy org.apache.nemo.compiler.optimizer.policy.StreamingPolicy` to set the Nemo Runner to streaming mode. Also, be sure to extend the `capacity` of the resources in the `resources.json`, for example: ``` { "type": "Reserved", "memory_mb": 2048, "capacity": 50000 } ``` Please refer to the for more information.