import os
import time
import threading
import psutil

class MemoryLogger:
    def __init__(self, filename, interval):
        self.stop_event = threading.Event()
        self.thread = threading.Thread(target=self.start, args=(filename, interval))
        self.thread.start()

    def __exit__(self, *args):
        self.stop_event.set()
        self.thread.join()

    def calculate_memory(self, proc):
        total_memory = proc.memory_info().rss
        for child in proc.children(recursive=True):
            total_memory += child.memory_info().rss
        return total_memory

    def start(self, filename, interval):
        with open(filename, 'w') as f:
            while not self.stop_event.is_set():
                process = psutil.Process(os.getpid())
                total_memory = self.calculate_memory(process)
                f.write(f"{time.time()} {total_memory / 10**6}\n")
                time.sleep(interval)

with MemoryLogger(filename='memory.log', interval=30.0):
    computationally_demanding_function()