BlockingProcessStreamReader.java doesn't log the error text and silently exits

[jainsahab]

BlockingProcessStreamReader.java is a separate thread which checks for blockUntil text to appear in it's constructor.
https://github.com/googleapis/java-core/blob/main/google-cloud-core/src/main/java/com/google/cloud/testing/BlockingProcessStreamReader.java#L47-L61

In cases where process is abruptly closed and resulted in non zero exit code, BlockingProcessStreamReader.java doesn't log the startup logs(which may contain the error information). This causes confusion to the end user.

Steps to reproduce

• Run gcloud beta emulators datastore startss (notice the typo in command) to check the error text we get on stdout.

➜  java-core git:(gh_issue_1038) ✗ gcloud beta emulators datastore startss
ERROR: (gcloud.beta.emulators.datastore) Invalid choice: 'startss'.
Maybe you meant:
  gcloud beta emulators datastore start
  gcloud beta emulators datastore env-init
  gcloud beta emulators datastore env-unset
  gcloud beta emulators bigtable start
  gcloud beta emulators firestore start
  gcloud beta emulators pubsub start

To search the help text of gcloud commands, run:
  gcloud help -- SEARCH_TERMS

• Execute below code and we can see that nothing is logged now.

import java.io.IOException;
import java.util.Arrays;
import java.util.logging.Logger;

public class Playground {

  public static void main(String[] args) throws IOException, InterruptedException {

    Process process = CommandWrapper.create()
        .setCommand(Arrays.asList("gcloud beta emulators datastore startss".split(" "))) // notice the typo in command
        .setRedirectErrorStream().start();
    BlockingProcessStreamReader blockingProcessStreamReader = BlockingProcessStreamReader.start(
        "test-playground", process.getInputStream(), "blockUntilOutput",
        Logger.getLogger(Playground.class.getName()));

    blockingProcessStreamReader.join();

    System.out.printf("Subprocess exit code: %d%n", process.exitValue()); // should print non zero value
  }

}

Ref: Similar issue happened in googleapis/java-datastore#355.

[jainsahab]

Hi @suztomo regarding googleapis/java-core#1039 (comment), #9108 is raised. let me know if you see any problem while reviewing this.

Thanks,