realtime log position to txt use python script

Can someone help me create a Python script to record positions in the event of a power loss or LinuxCNC error?

I plan to create an external real-time position logger with an update interval of 0.001 seconds. I use this feature for a wirecut machine. I'm using a Python script and have tried activating log_position_to_txt.py with the M-code command, but the position logging process results in a code overflow, causing the .txt file to grow uncontrollably.

Here's the code for log_position_to_txt.py:

##############################
#!/usr/bin/env python2.7
import linuxcnc
import time

stat = linuxcnc.stat()

with open("position-log.txt", "w") as outfile:

while True:

stat.poll()
x,y,z,a,b,c,u,v,w = stat.actual_position

outfile.write("X ")
outfile.write("{:.4f}\n".format(x))
outfile.write("Y ")
outfile.write("{:.4f}\n".format(y))

time.sleep(0.001)
####################################


Can someone help me fix my Python script so that... position recording does not result in code accumulation?

better use python3

Thanks for your help. But position-log.txt doesn't show up to record.

I'm using LinuxCNC 2.8.4 Debian Buster.

I've tried POSITION_FILE, but it can only save the position when linuxcnc is closed normally. When my PC is suddenly turned off, such as due to a power outage or linuxcnc error, POSITION_FILE doesn't save the last position of the machine movement.

I've tried it on LinuxCNC 7.4.15 Debian Wheezy. While LinuxCNC is running, coordinates aren't saved when the power outages.

The last coordinates are only saved when LinuxCNC is closed normally.

Just an idea.
The last position that will be recorded will be the last data that that was successfully written to the hardware from the file buffer.
Now the power going out will be for all intents and purposes a random event, there is no guarantee that any particular data will be successfully written to hardware before a power outage.
The only way I can see everything happening gracefully is with a UPS, that once detects a mains outage is able to shutdown gracefully. But the machine itself may not be in the exact position you expect due to inertia and any other unknown factors mechanical or electrical.
So basically data not being written the disk is more of a limitation of an OS when power is removed suddenly.
Also one would hope the file being written to is not stored in tmpfs (ram) then written to disc during the shutdown process of Linuxcnc.