nicnguyen3103 opened a new issue, #36885:
URL: https://github.com/apache/airflow/issues/36885
### Apache Airflow version
2.8.0
### If "Other Airflow 2 version" selected, which one?
_No response_
### What happened?
Using PostgresSQL backend, and an empty DagFolder, running command `airflow
dag-processor` return the following error
```
2024-01-19T13:11:23.238+0700] {settings.py:61} INFO - Configured default
timezone Timezone('UTC')
[2024-01-19T13:11:23.265+0700] {dag_processor_job_runner.py:60} INFO -
Starting the Dag Processor Job
[2024-01-19T13:11:23.283+0700] {dag_processor_job_runner.py:64} ERROR -
Exception when executing DagProcessorJob
Traceback (most recent call last):
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/jobs/dag_processor_job_runner.py",
line 62, in _execute
self.processor.start()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/dag_processing/manager.py",
line 475, in start
return self._run_parsing_loop()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/dag_processing/manager.py",
line 558, in _run_parsing_loop
ready = multiprocessing.connection.wait(self.waitables.keys(),
timeout=poll_time)
AttributeError: module 'multiprocessing' has no attribute 'connection'
Traceback (most recent call last):
File "/Users/nic/.virtualenvs/airflow-migration/bin/airflow", line 8, in
<module>
sys.exit(main())
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/__main__.py",
line 57, in main
args.func(args)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/cli/cli_config.py",
line 49, in command
return func(*args, **kwargs)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/utils/cli.py",
line 114, in wrapper
return f(*args, **kwargs)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/utils/providers_configuration_loader.py",
line 55, in wrapped_function
return func(*args, **kwargs)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/cli/commands/dag_processor_command.py",
line 65, in dag_processor
run_command_with_daemon_option(
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/cli/commands/daemon_utils.py",
line 86, in run_command_with_daemon_option
callback()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/cli/commands/dag_processor_command.py",
line 68, in <lambda>
callback=lambda: run_job(job=job_runner.job,
execute_callable=job_runner._execute),
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/utils/session.py",
line 79, in wrapper
return func(*args, session=session, **kwargs)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/jobs/job.py",
line 393, in run_job
return execute_job(job, execute_callable=execute_callable)
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/jobs/job.py",
line 422, in execute_job
ret = execute_callable()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/jobs/dag_processor_job_runner.py",
line 62, in _execute
self.processor.start()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/dag_processing/manager.py",
line 475, in start
return self._run_parsing_loop()
File
"/Users/nic/.virtualenvs/airflow-migration/lib/python3.10/site-packages/airflow/dag_processing/manager.py",
line 558, in _run_parsing_loop
ready = multiprocessing.connection.wait(self.waitables.keys(),
timeout=poll_time)
AttributeError: module 'multiprocessing' has no attribute 'connection'. Did
you mean: 'Condition'?
```
Adding a single dag inside the dag folder fix the issue:
```
[2024-01-19T13:16:47.159+0700] {settings.py:61} INFO - Configured default
timezone Timezone('UTC')
[2024-01-19T13:16:47.193+0700] {dag_processor_job_runner.py:60} INFO -
Starting the Dag Processor Job
```
### What you think should happen instead?
DagProcessor should be running regardless of dag folder empty or not
### How to reproduce
Running `airflow dag-processor` command with an empty dag folder with
PostgresSQL backend
### Operating System
MacOS
### Versions of Apache Airflow Providers
apache-airflow==2.8.0
apache-airflow-providers-common-sql==1.10.0
apache-airflow-providers-ftp==3.7.0
apache-airflow-providers-http==4.8.0
apache-airflow-providers-imap==3.5.0
apache-airflow-providers-sqlite==3.7.0
### Deployment
Official Apache Airflow Helm Chart
### Deployment details
_No response_
### Anything else?
_No response_
### Are you willing to submit PR?
- [ ] Yes I am willing to submit a PR!
### Code of Conduct
- [X] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
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