Apache Flink® Troubleshooting Training

Introduction

This repository provides the basis of the hands-on part of the "Apache Flink Troubleshooting" training session at Flink Forward Europe 2019.

Requirements

To make use of this repository participants will need:

• git
• JDK 8
• maven
• a Java IDE (Intellij IDEA/Eclipse)

Training Preparations

In order to avoid potential issues with the WiFi at the training venue, please checkout and build the project prior to the training:

git clone git@github.com:ververica/flink-training-troubleshooting.git
cd flink-training-troubleshooting
mvn clean package

Infrastructure

During the training, participants will be asked to run the Flink job TroubledStreamingJob locally as well as on Ververica Platform.

Running Locally

Just run the test in TroubledStreamingJobRunner which will call the main-method of TroubledStreamingJob with a local configuration and automatically pulls in dependencies with "provided" scope.

Once running, you can access Flink's Web UI via http://localhost:8081.

The Flink Job

This simple Flink job reads measurement data from a Kafka topic with eight partitions. For the purpose of this training the KafkaConsumer is replaced by FakeKafkaSource. The result of a calculation based on the measurement value is averaged over 1 second. The overall flow is depicted below:

+-------------------+     +-----------------------+     +-----------------+     +----------------------+     +--------------------+
|                   |     |                       |     |                 |     |                      |     |                    |
| Fake Kafka Source | --> | Watermarks/Timestamps | --> | Deserialization | --> | Windowed Aggregation | --> | Sink: NormalOutput |
|                   |     |                       |     |                 |     |                      |     |                    |
+-------------------+     +-----------------------+     +-----------------+     +----------------------+     +--------------------+
                                                                                            \
                                                                                             \               +--------------------+
                                                                                              \              |                    |
                                                                                               +-----------> | Sink: LateDataSink |    
                                                                                                             |                    |
                                                                                                             +--------------------+

In local mode, sinks print their values on stdout (NormalOutput) and stderr (LateDataSink) for simplified debugging while as without local mode, a DiscardingSink is used for each sink.

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