[Python] fastapi workers die in add_basemap

I have a problem with add_basemap from contextily. (I'm new to this to be honest)

I use fastapi in docker with workers=4, and contextily to make images. In random time it die add_basemap (I don't know why), in logs i can see

fastapi-1 | 2025-07-29 11:40:16,934 - logs_storage.logs_storage - INFO - Saving summary image
fastapi-1 | 2025-07-29 11:40:26,967 - logs_uploader.save_image - WARNING - Adding basemaps timed out after 10 seconds — proceeding without them.
fastapi-1 | INFO: Waiting for child process [361]
fastapi-1 | INFO: Child process [361] died


I thought that signal will help me, but it didn't

class TimeoutException(Exception):
pass

def _timeout_handler(signum: int, frame) -> None:
raise TimeoutException("Timeout while adding basemap")


signal.signal(signal.SIGALRM, _timeout_handler)
signal.alarm(ADD_BASEMAP_TIMEOUT)
try:
ctx.add_basemap(ax, source=ctx.providers.Esri.WorldImagery, crs="EPSG:3857", alpha=1.0) # pyright: ignore
ctx.add_basemap(ax, source=ctx.providers.CartoDB.PositronOnlyLabels, crs="EPSG:3857", alpha=0.95) # pyright: ignore
_LOGGER.info("Basemaps added successfully")
except TimeoutException:
_LOGGER.warning(f"Adding basemaps timed out after {ADD_BASEMAP_TIMEOUT} seconds — proceeding without them.")
except Exception as e:
_LOGGER.warning(f"Error adding basemap: {e}")
finally:
signal.alarm(0)


I also try ThreadPoolExecutor, but it also doesn't work

Continue reading...