Loguru error when using dask with a multiprocessing scheduler

Question

I'm getting a RuntimeError when trying to log from a dask.delayed function using a logger handler with enqueue enabled.

Here's a minimal reproducible example

import sys, dask
from loguru import logger

logger.add(sys.stderr, enqueue=True)

@dask.delayed
def log():
    logger.info("Logging!")

dask.compute(*[log() for i in range(10)], scheduler="processes")

Which produces the following error:

RuntimeError: SimpleQueue objects should only be shared between processes through inheritance

score 0 · Answer 1 · answered Sep 14 '22 at 04:43

The solution is simple. Import the logger from within your delayed function:

In [1]: import sys, dask
   ...: from loguru import logger
   ...: 
   ...: logger.add(sys.stderr, enqueue=True)
   ...: 
   ...: @dask.delayed
   ...: def log():
   ...:     from loguru import logger
   ...:     logger.info("Logging!")
   ...: 
   ...: dask.compute(*[log() for i in range(10)], scheduler="processes")
2022-09-13 21:42:36.001 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.001 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.001 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.001 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.002 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.002 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.004 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.004 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.004 | INFO     | __main__:log:9 - Logging!
2022-09-13 21:42:36.004 | INFO     | __main__:log:9 - Logging!
Out[1]: (None, None, None, None, None, None, None, None, None, None)

Loguru error when using dask with a multiprocessing scheduler

1 Answers1