import time
from concurrent.futures import ProcessPoolExecutor
def fail():
time.sleep(1)
raise ValueError()
executor = ProcessPoolExecutor(max_workers=1, max_tasks_per_child=1)
try:
print(executor.submit(fail).exception() is not None)
finally:
executor.shutdown(wait=False)Exception in thread Thread-1:
Traceback (most recent call last):
File "python3.11/threading.py", line 1045, in _bootstrap_inner
self.run()
File "python3.11/concurrent/futures/process.py", line 364, in run
executor._adjust_process_count()
File "python3.11/concurrent/futures/process.py", line 759, in _adjust_process_count
process_count = len(self._processes)
^^^^^^^^^^^^^^^^^^^^
TypeError: object of type 'NoneType' has no len()
If you change the code to using wait=True, or remove the max_tasks_per_child=1 option then the message is not printed.
Bug report
Bug description:
If you run this, then the following is printed to the console:
If you change the code to using wait=True, or remove the max_tasks_per_child=1 option then the message is not printed.
Probably the fix is just to check if self.processes is None before accessing it at https://github.com/python/cpython/blob/main/Lib/concurrent/futures/process.py#L762
CPython versions tested on:
3.11
Operating systems tested on:
Linux
Linked PRs