Thread on Core 1 on PICO hangs when accessing io

Port, board and/or hardware

Raspberry Pi Pico

MicroPython version

MicroPython v1.23.0 on 2024-06-02; Raspberry Pi Pico with RP2040

Reproduction

import os
import time
import _thread


def core1_thread():
    try:
        print("entering core1_thread")
        text = "some text to log"
        # Open log file in append mode
        f = open("test.log", "a")
        f.write(text)
    except OSError as ex:
        print(ex)
    finally:
        f.close()


def create_log():
    """
    Check if the log file exists. If the log file does not exist, create the log file and write a header line.

    Parameters:
        None

    Returns:
        None
    """
    _log_fn = "/test.log"
    try:
        # File exists
        os.stat(_log_fn)
        return
    except OSError:
        idx = _log_fn.rfind("/")
        dir = _log_fn[1:idx]
        if dir and not dir in os.listdir():
            os.mkdir(dir)
        # File does not exist
        try:
            t = f"file {_log_fn} created\n"
            with open(_log_fn, "a") as f:
                f.write(t)
                print(t.rstrip())
        except OSError as ex:
            raise OSError(f"exception {ex}")


def main():
    create_log()
    thread = _thread.start_new_thread(core1_thread, ())

if __name__ == "__main__":
    main()
    time.sleep(1)  # if 'mpremote run', allow thread to run before we soft reset

Expected behaviour

Expected to see 'some text to log' in file test.log on pico.

Observed behaviour

After starting the thread it hangs after printing 'entering core1_thread'.

Additional Information

No, I've provided everything above.

Code of Conduct

Yes, I agree