Thread on Core 1 on PICO hangs when accessing io #15982

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