Open AntoniLuongPham opened 4 years ago
BUG.SameMotor.Threading.EV3Dev2.MicroPython.py
#!/usr/bin/env micropython
from ev3dev2.motor import MediumMotor, OUTPUT_A
from ev3dev2.sensor import INPUT_1, INPUT_4
from ev3dev2.sensor.lego import TouchSensor, InfraredSensor
from threading import Thread
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
IR_SENSOR = InfraredSensor(address=INPUT_4)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.on_for_seconds(
speed=100,
seconds=1,
brake=True,
block=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons_pressed(channel=1):
MOTOR.on_for_seconds(
speed=-100,
seconds=1,
brake=True,
block=True)
Thread(target=touch_to_turn_motor_clockwise).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# *** BUG as of 2020 ***
# *** just the presence of the above parallel Thread makes this main thread crash ***
# Traceback (most recent call last):
# File "/home/robot/test/BUG.SameMotor.Threading.EV3Dev2.MicroPython.py", line 38, in <module>
# File "/home/robot/test/BUG.SameMotor.Threading.EV3Dev2.MicroPython.py", line 29, in press_any_ir_remote_button_to_turn_motor_counterclockwise
# File "ev3dev2/motor.py", line 1048, in on_for_seconds
# File "ev3dev2/motor.py", line 928, in wait_until_not_moving
# File "ev3dev2/motor.py", line 908, in wait
# OSError: 4
BUG.SameMotor.Threading.EV3Dev2.Python3.py
#!/usr/bin/env python3
from ev3dev2.motor import MediumMotor, OUTPUT_A
from ev3dev2.sensor import INPUT_1, INPUT_4
from ev3dev2.sensor.lego import TouchSensor, InfraredSensor
from threading import Thread
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
IR_SENSOR = InfraredSensor(address=INPUT_4)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.on_for_seconds(
speed=100,
seconds=1,
brake=True,
block=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons_pressed(channel=1):
MOTOR.on_for_seconds(
speed=-100,
seconds=1,
brake=True,
block=True)
Thread(target=touch_to_turn_motor_clockwise,
daemon=True).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# *** BUG as of 2020 ***
# *** as soon as both Touch Sensor and an IR button are pressed ***
# Traceback (most recent call last):
# File "/home/robot/test/BUG.SameMotor.Threading.EV3Dev2.Python3.py", line 39, in <module>
# press_any_ir_remote_button_to_turn_motor_counterclockwise()
# File "/home/robot/test/BUG.SameMotor.Threading.EV3Dev2.Python3.py", line 33, in press_any_ir_remote_button_to_turn_motor_counterclockwise
# block=True)
# File "/usr/lib/python3/dist-packages/ev3dev2/motor.py", line 1048, in on_for_seconds
# self.wait_until_not_moving()
# File "/usr/lib/python3/dist-packages/ev3dev2/motor.py", line 928, in wait_until_not_moving
# return self.wait(lambda state: self.STATE_RUNNING not in state or self.STATE_STALLED in state, timeout)
# File "/usr/lib/python3/dist-packages/ev3dev2/motor.py", line 908, in wait
# self._poll.poll(poll_tm)
# RuntimeError: concurrent poll() invocation
SameMotor.MultiProcessing.EV3Dev2.MicroPython.py
#!/usr/bin/env micropython
from ev3dev2.motor import MediumMotor, OUTPUT_A
from ev3dev2.sensor import INPUT_1, INPUT_4
from ev3dev2.sensor.lego import TouchSensor, InfraredSensor
from multiprocessing import Process
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
IR_SENSOR = InfraredSensor(address=INPUT_4)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.on_for_seconds(
speed=100,
seconds=1,
brake=True,
block=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons_pressed(channel=1):
MOTOR.on_for_seconds(
speed=-100,
seconds=1,
brake=True,
block=True)
Process(target=touch_to_turn_motor_clockwise).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# observation: both processes run successfully WITH mutual blocking
# i.e. 1 process CANNOT interrupt/reverse the other process's Motor movement mid-stream
SameMotor.MultiProcessing.EV3Dev2.Python3.py
#!/usr/bin/env python3
from ev3dev2.motor import MediumMotor, OUTPUT_A
from ev3dev2.sensor import INPUT_1, INPUT_4
from ev3dev2.sensor.lego import TouchSensor, InfraredSensor
from multiprocessing import Process
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
IR_SENSOR = InfraredSensor(address=INPUT_4)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.on_for_seconds(
speed=100,
seconds=1,
brake=True,
block=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons_pressed(channel=1):
MOTOR.on_for_seconds(
speed=-100,
seconds=1,
brake=True,
block=True)
Process(target=touch_to_turn_motor_clockwise,
daemon=True).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# observation: both processes run successfully WITH mutual blocking
# i.e. 1 process CANNOT interrupt/reverse the other process's Motor movement mid-stream
SameMotor.Threading.EV3Dev1.py
#!/usr/bin/env python3
from ev3dev.ev3 import TouchSensor, INPUT_1, InfraredSensor, INPUT_4, RemoteControl, MediumMotor, OUTPUT_A
from threading import Thread
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
REMOTE_CONTROL = RemoteControl(sensor=InfraredSensor(address=INPUT_4),
channel=1)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.run_timed(
speed_sp=1000, # deg/s
time_sp=1000, # ms
stop_action=MediumMotor.STOP_ACTION_HOLD)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if REMOTE_CONTROL.buttons_pressed:
MOTOR.run_timed(
speed_sp=-1000, # deg/s
time_sp=1000, # ms
stop_action=MediumMotor.STOP_ACTION_HOLD)
Thread(target=touch_to_turn_motor_clockwise,
daemon=True).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# observation: both threads run successfully WITHOUT mutual blocking
# i.e. 1 thread CAN interrupt/reverse the other thread's Motor movement mid-stream
SameMotor.MultiProcessing.EV3Dev1.py
#!/usr/bin/env python3
from ev3dev.ev3 import TouchSensor, INPUT_1, InfraredSensor, INPUT_4, RemoteControl, MediumMotor, OUTPUT_A
from multiprocessing import Process
TOUCH_SENSOR = TouchSensor(address=INPUT_1)
REMOTE_CONTROL = RemoteControl(sensor=InfraredSensor(address=INPUT_4),
channel=1)
MOTOR = MediumMotor(address=OUTPUT_A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.is_pressed:
MOTOR.run_timed(
speed_sp=1000, # deg/s
time_sp=1000, # ms
stop_action=MediumMotor.STOP_ACTION_HOLD)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if REMOTE_CONTROL.buttons_pressed:
MOTOR.run_timed(
speed_sp=-1000, # deg/s
time_sp=1000, # ms
stop_action=MediumMotor.STOP_ACTION_HOLD)
Process(target=touch_to_turn_motor_clockwise,
daemon=True).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# observation: both processes run successfully WITHOUT any mutual blocking
# i.e. 1 process CAN interrupt/reverse the other process's Motor movement mid-stream
SameMotor.Threading.PyBricks.py
#!/usr/bin/env pybricks-micropython
from pybricks.ev3devices import TouchSensor, InfraredSensor, Motor
from pybricks.parameters import Port, Stop
from threading import Thread
TOUCH_SENSOR = TouchSensor(port=Port.S1)
IR_SENSOR = InfraredSensor(port=Port.S4)
MOTOR = Motor(port=Port.A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.pressed():
MOTOR.run_time(
speed=1000, # deg/s
time=1000, # ms
then=Stop.HOLD,
wait=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons(channel=1):
MOTOR.run_time(
speed=-1000, # deg/s
time=1000, # ms
then=Stop.HOLD,
wait=True)
Thread(target=touch_to_turn_motor_clockwise).start()
press_any_ir_remote_button_to_turn_motor_counterclockwise()
# observation: both threads run successfully WITH mutual blocking
# i.e. 1 thread CANNOT interrupt/reverse the other thread's Motor movement mid-stream
SameMotor.RunParallel.PyBricks.py
#!/usr/bin/env pybricks-micropython
from pybricks.ev3devices import TouchSensor, InfraredSensor, Motor
from pybricks.parameters import Port, Stop
from pybricks.experimental import run_parallel
TOUCH_SENSOR = TouchSensor(port=Port.S1)
IR_SENSOR = InfraredSensor(port=Port.S4)
MOTOR = Motor(port=Port.A)
def touch_to_turn_motor_clockwise():
while True:
if TOUCH_SENSOR.pressed():
MOTOR.run_time(
speed=1000, # deg/s
time=1000, # ms
then=Stop.HOLD,
wait=True)
def press_any_ir_remote_button_to_turn_motor_counterclockwise():
while True:
if IR_SENSOR.buttons(channel=1):
MOTOR.run_time(
speed=-1000, # deg/s
time=1000, # ms
then=Stop.HOLD,
wait=True)
run_parallel(
touch_to_turn_motor_clockwise,
press_any_ir_remote_button_to_turn_motor_counterclockwise)
# observation: both threads run successfully WITH mutual blocking
# i.e. 1 thread CANNOT interrupt/reverse the other thread's Motor movement mid-stream
Yeah, multi-threaded access to the same motor is not (officially) supported, unfortunately. It's curious that your results seem to indicate that stock motors work un-modified with the v1.0 series; I am not sure why there's a difference there, probably due to blocking logic changes. It might be worth diffing the motor code to compare, but then again, since we haven't intentionally designed it to work with concurrent access I don't expect that to be consistent.
My suggestion is to go with the mutex version to be safe.
@WasabiFan the most curious result among the above is from Program no. 1 "BUG.SameMotor.Threading.EV3Dev2.MicroPython.py": the program crashes even when the Touch Sensor is never touched and hence its related Thread
never actually attempts to access the Motor. What do you make of this?
Is there a MicroPython compiler that compiles this program and identifies that there is a chance that the Touch-Sensor-related Thread
may access the Motor?
That case sounds like this other one: https://github.com/ev3dev/ev3dev-lang-python/issues/727
OSError 4 is EINTR, i.e. "system call interrupted". It means that a signal was raised while in a system call, and the system call was aborted to prevent deadlock. This happens because even just the presence of threads means the interpreter (Micropython specifically) will begin triggering signals to synchronize garbage collection.
Technical overview aside, it means that multithreading does not play nice with our MicroPython library, unfortunately. I had tried to work toward a true solution of this (starting with https://github.com/ev3dev/ev3dev-lang-python/pull/732, to benchmark the speed of our library before adding error handling) but haven't circled back to finish it, implement the error handling, and re-benchmark. There are some notes at the bottom of the thread linked above which might help you work around it.
We are also getting OSError: 4 errors in wait a significant number of times in micropython. If we shut off odometry_start() from MoveDifferential , would it remove the problem?
Ah, yeah, odometry uses a thread in the background and may provoke EINTR.
Thanks
ev3dev version: 4.14.117-ev3dev-2.3.5-ev3
I have certain programs that crash on EV3Dev2 when 2 parallel
Thread
s may control the same Motor. The crashes have different error messages on MicroPython vs. Python3. I have reproduced the errors in the enclosed test scripts "BUG.SameMotor.Threading.EV3Dev2.MicroPython.py" and "BUG.SameMotor.Threading.EV3Dev2.Python3.py".For comparison, I have also tried and enclosed below other variations (e.g. using
ev3dev
(1.2.0) orpybricks
instead ofev3dev2
, or usingmultiprocessing
or PyBricks'srun_parallel
instead ofthreading
) that run successfully.All these programs do the following: turn the Motor clockwise when the Touch Sensor is pressed, or turn the same Motor counter-clockwise when any IR Remote Control button is pressed. The observations from all the coding variations are as follows:
threading
withev3dev2
2.1.0 onmicropython
: CRASHED after pressing the IR Remote Control buttons a few times (making the Motor turn counter-clockwise), even if the Touch Sensor is NOT pressed at all (i.e. that Touch-Sensor-triggeredThread
never commands the Motor at all).threading
withev3dev2
2.1.0 onpython3
: CRASHED when the Touch Sensor and an IR Remote Control button are pressed at the same time, i.e. bothThread
are trying to command the Motor at the same time. But the program runs ok when only 1 button is pressed.multiprocessing
withev3dev2
2.1.0 onmicropython
: bothProcess
es run successfully WITH mutual blocking, i.e. 1Process
CANNOT interrupt/reverse the otherProcess
's Motor movement mid-streammultiprocessing
withev3dev2
2.1.0 onpython3
: bothProcess
es run successfully WITH mutual blocking, i.e. 1Process
CANNOT interrupt/reverse the otherProcess
's Motor movement mid-streamthreading
withev3dev
(1.2.0) onpython3
: bothThread
s run successfully WITHOUT mutual blocking, i.e. 1Thread
CAN interrupt/reverse the otherThread
's Motor movement mid-streammultiprocessing
withev3dev
(1.2.0) onpython3
: bothProcess
es run successfully WITHOUT mutual blocking, i.e. 1Process
CAN interrupt/reverse the otherProcess
's Motor movement mid-streamthreading
withpybricks
(2.0.0) onpybricks-micropython
: bothThread
s run successfully WITH mutual blocking, i.e. 1Thread
CANNOT interrupt/reverse the otherThread
's Motor movement mid-streamrun_parallel
(experimental PyBricks feature) withpybricks
(2.0.0) onpybricks-micropython
: bothThread
s run successfully WITH mutual blocking, i.e. 1Thread
CANNOT interrupt/reverse the otherThread
's Motor movement mid-stream