Importlib.reload Does Not Reload Programmatically Generated File

The second assertion fails, indicating that importlib.reload silently failed to reload the modified module, can anyone explain why? import os import sys import tempfile import impo

Solution 1:

The following code, extended with time.sleep(10) doesn't throw the assertion error (the safe threshold appear to be one second). This provides the explanation why the reload didn't work as expected. So the answer to the question why the assertion error is raised is

importlib.reload() uses file timestamp to decide about re-compiling the cached file.

If the code update/change happens very fast, the cached and the script file are considered to be the same version and there is no re-compiling of the cached files from which modules are re-loaded.

import os
import sys
import tempfile
import importlib
import time

# Create some module and import itdir = tempfile.TemporaryDirectory()
os.mkdir(os.path.join(dir.name, 'test_package'))
withopen(os.path.join(dir.name, '__init__.py'), "w") as f:
    f.write("\n")
withopen(os.path.join(dir.name, 'test_package', 'some_module.py'), "w") as f:
    f.write("def a():\n    print(\"old\")\n    return 0\n")
sys.path.insert(0, dir.name)

from test_package import some_module

# Check that imported code works as expectedassert some_module.a() == 0

time.sleep(10)

# Alter module and reloadwithopen(os.path.join(dir.name, 'test_package', 'some_module.py'), "w") as f:
    f.write("def a():\n    print(\"new\")\n    return 1\n")

importlib.reload(some_module)

# Check wether modifications have been reloadedassert some_module.a() == 1

sys.path.pop(0)