Debug with localrun mode

In localrun mode, a function consumes and produces actual data to a Pulsar cluster, and mirrors how the function runs in a Pulsar cluster. This provides a way to test your function and allows you to launch a function instance on your local machine as a thread for easy debugging.

Debug with localrun mode - 图1note

Debugging with localrun mode is only available for Java functions in Pulsar 2.4.0 or later versions.

Before using localrun mode, you need to add the following dependency.

  1. <dependency>
  2.     <groupId>org.apache.pulsar</groupId>
  3.     <artifactId>pulsar-functions-local-runner-original</artifactId>
  4.     <version>${pulsar.version}</version>
  5. </dependency>
  7. <dependency>
  8.     <groupId>com.google.protobuf</groupId>
  9.     <artifactId>protobuf-java</artifactId>
  10.     <version>3.21.9</version>
  11. </dependency>

For example, you can run your function in the following manner.

  1. FunctionConfig functionConfig = new FunctionConfig();
  2. functionConfig.setName(functionName);
  3. functionConfig.setInputs(Collections.singleton(sourceTopic));
  4. functionConfig.setClassName(ExclamationFunction.class.getName());
  5. functionConfig.setRuntime(FunctionConfig.Runtime.JAVA);
  6. functionConfig.setOutput(sinkTopic);
  8. LocalRunner localRunner = LocalRunner.builder().functionConfig(functionConfig).build();
  9. localRunner.start(true);

You can debug functions using an IDE. Set breakpoints and manually step through a function to debug with real data.

The following code example shows how to run a function in localrun mode.

  1. public class ExclamationFunction implements Function<String, String> {
  3.     @Override
  4.     public String process(String s, Context context) throws Exception {
  5.         return s + "!";
  6.     }
  8.     public static void main(String[] args) throws Exception {
  9.         FunctionConfig functionConfig = new FunctionConfig();
  10.         functionConfig.setName("exclamation");
  11.         functionConfig.setInputs(Collections.singleton("input"));
  12.         functionConfig.setClassName(ExclamationFunction.class.getName());
  13.         functionConfig.setRuntime(FunctionConfig.Runtime.JAVA);
  14.         functionConfig.setOutput("output");
  16.         LocalRunner localRunner = LocalRunner.builder().functionConfig(functionConfig).build();
  17.         localRunner.start(false);
  18.     }
  19. }