Pyodide doesn't recognize changes in files using the Emscripten File System API.

🐛 Bug

When I’m using  pyodide.FS the method writeFile Pyodide doesn’t recognize changes in files.

To Reproduce

1. Create a file using FS.writeFile, like this:

const content = `
def hello():
  return 'hello v1'
`;
pyodide.FS.writeFile('my_mod.py', content );

1. Check the content by FS.readFile

const contentPy = pyodide.FS.readFile('my_mod.py');
const string = new TextDecoder().decode(contentPy);
console.log(string) // print content

1. Now, execute code by runPython.

pyodide.runPython(`
    import my_mod
    print(my_mod.hello())
`);

1. Check stdout, show the result:

hello v1

Here all fine!

1. But, when I make any change in my_mod.py content with FS.writeFile Pyodide doesn’t recognize the changes. For example:

const newContent= `
def hello():
  return 'change'
`;
pyodide.FS.writeFile('my_mod.py', content );
pyodide.runPython(`
    import my_mod
    print(my_mod.hello())
`);

1. Pyodide shows in stdout the old version file, check stdout:

hello v1
hello v1

Expected behavior

Pyodide should recognize changes in files using the Emscripten File System API.

Environment

• Pyodide Version: 0.21.3

Additional context

I create a demo in this stackblitz project to explain the bug.

[hoodmane]

This would probably be another good faq entry.

[nicobytes]

@hoodmane great!

I tried your approach, which works here in my demo and now I have an idea for not running the 5 steps again.

The next week, I’ll send a PR with improvements in the docs. 🙂