When you encounter a function in your Prefect 2.0 pipeline that is hanging and not providing enough information through

<http://logger.info|logger.info>

statements, here are several tips and tricks you can use to debug the issue: 1. Increase Logging Level: Elevate the logging level to

DEBUG

to gain more insight into what’s happening behind the scenes. You might be able to see more granular logs which could hint at where the process is stalling. 2. Insert Manual Print Statements: Although not always recommended for production code, inserting

print()

statements before and after certain lines can help identify the last point of successful execution. 3. Use a Debugger: Employ a debugger tool (like

pdb

for Python) to step through your code execution. By setting breakpoints, you can inspect the current state and step line by line to find where it hangs. 4. Timing Decorators: Write a decorator that logs the start and end time of function execution. This might help you pinpoint which part of the function is taking long. 5. Memory and Resource Monitoring: If the hanging might be due to resource constraints, monitor the memory and CPU usage during the function execution. This could indicate if you're running into resource limits. 6. External Service Timeouts: If your function depends on external services or I/O, ensure you have reasonable timeouts in place and are handling potential exceptions that may arise from such calls. 7. Concurrency Issues: In case the function that hangs involves concurrency or parallel processing, look out for deadlocks or race conditions that could cause the hang up. 8. Cut Down the Function: If possible, split the function into smaller parts and test these parts independently to isolate issues. 9. Reproduce in Isolation: Try to simulate the function’s environment and run it in isolation from the rest of the workflow. If it runs successfully independently, the issue might be in its interaction with other parts of the code. 10. Profiler: Use a profiling tool to analyze the execution of your code. This can help identify bottlenecks or infinite loops that are not obvious. 11. Task Logs: If your function is part of a flow run, check the Prefect UI for task logs that might give hints as to what's happening. 12. Check for Updates: Ensure you're using the latest version of Prefect and its dependencies. Sometimes, bugs that cause hanging can be resolved by updating to the latest versions. Remember that debugging may require a combination of these methods to pinpoint the issue effectively. Also, don't hesitate to reach out to the community or Prefect support if you feel stuck, as others might have experienced similar issues.

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