Azure Data Factory中U-SQL Activity执行失败问题咨询

Hey there, let's troubleshoot this frustrating issue you're hitting with Azure Data Factory (ADF) and your U-SQL job. Since the script runs perfectly in Visual Studio and directly via Data Lake Analytics (ADLA), the problem is almost tied to how ADF is handling the job execution or configuration. Here are the key areas to check first:

• Service Principal Access: Double-check that the service principal used by your ADLA linked service in ADF has the right permissions on your Azure Data Lake Storage (ADLS) account. Even if you can run the job manually, the ADF identity might lack Read access to the copied input files or Write access to the output path. Test this by logging into ADLS with the service principal's credentials to confirm it can access the files.
• Linked Service Configuration: Ensure your ADLA linked service points to the correct ADLA account and that any authentication settings (like service principal credentials) are up-to-date.

ADLS can sometimes have a small propagation delay after a copy activity completes—even if ADF marks the copy as successful, the files might not be fully visible to ADLA immediately. Try adding a Wait Activity between your copy and U-SQL activities (set it to 30-60 seconds) to give the files time to be fully committed.

• Path Consistency: If your script uses relative paths when running locally, ADF might resolve them differently. Switch to absolute paths in the script, or use ADF parameters to dynamically inject the correct input/output paths that match where the copy activity wrote the files.
• Parameter Validation: Confirm that all parameters your U-SQL script expects are being passed correctly from ADF. For example, if your script uses @InputFolder, make sure the ADF activity is setting this parameter to the exact folder path from the copy activity's output.
• Add File Existence Checks: Insert a check in your U-SQL script to confirm the input files exist before processing—this will give you a clearer error if the files aren't accessible:

  DECLARE @InputPath string = "/raw/uploaded_data.csv";
  IF NOT EXISTS(ADL.FILE(@InputPath)) THEN
      THROW "Input file missing: " + @InputPath;
  END;
  

You mentioned the error starts with "JSON Defini..."—make sure to pull the complete error message from ADF's activity run details:

• ADLA Job ID: Grab the job ID from the error and look it up directly in the ADLA portal. The job logs there often reveal the root cause (like permission denied, missing files, or syntax issues that only surface when run via ADF).
• ADF Activity JSON: Check the JSON configuration of your U-SQL activity (from the ADF portal's "Code" view) for syntax errors—missing commas, invalid parameter names, or incorrect paths are common culprits here.

When you run the U-SQL job manually, you might be using specific resource settings (like degree of parallelism, memory per node) that aren't set in ADF. Compare these settings and adjust the Advanced Settings in your ADF U-SQL activity to match the ones that work for manual runs. Quota limits or under-provisioned resources can cause immediate failures when ADF submits the job.

If you can share the full error message or a snippet of your ADF activity's JSON configuration, we can narrow this down even further—but these steps should cover most of the common causes!

内容的提问来源于stack exchange，提问作者Waqas Idrees