我正在使用 Raspberry Pi (3 B+) 制作數據收集設備，我正在嘗試生成一個進程來記錄傳入的數據并將其寫入文件。我有一個寫作函數，當我直接調用它時可以正常工作。然而，當我使用多進程方法調用它時，似乎什么也沒發生。我可以在 Linux 的任務監視器中看到該進程確實被生成但沒有文件被寫入，并且當我嘗試將標志傳遞給它以關閉它時它不起作用，這意味著我最終終止了該進程而什么也沒有似乎已經發生了。我已經從各個方面解決了這個問題，但看不出我做錯了什么；還有其他人嗎？如果相關，這些是父類中的函數，其中一個函數旨在生成另一個作為線程的函數。我正在使用的代碼：from datetime import datetime, timedeltaimport csvfrom drivers.IMU_SEN0 import IMU_SEN0import multiprocessing, osclass IMU_data_logger:? ? _output_filename = ''? ? _csv_headers = []? ? _accelerometer_headers = ['Accelerometer X','Accelerometer? ? Y','Accelerometer Z']? ? _gyroscope_headers = ['Gyroscope X','Gyroscope Y','Gyroscope Z']? ? _magnetometer_headers = ['Bearing']? ? _log_accelerometer = False? ? _log_gyroscope= False? ? _log_magnetometer = False? ? IMU = None? ? _writer=[]? ? _run_underway = False? ? _process=[]? ? _stop_value = 0def __init__(self,output_filename='/home/pi/blah.csv',log_accelerometer = True,log_gyroscope= True,log_magnetometer = True):? ? """data logging device? ? NOTE! Multiple instances of this class should not use the same IMU devices simultaneously!"""? ? ? ??? ? self._output_filename = output_filename? ? self._log_accelerometer = log_accelerometer? ? self._log_gyroscope = log_gyroscope? ? self._log_magnetometer = log_magnetometerdef __del__(self):? ? # TODO Update this? ? if self._run_underway: # If there's still a run underway, end it first? ? ? ? self.end_recording()def _set_up(self):? ? ? ??? ? self.IMU = IMU_SEN0(self._log_accelerometer,self._log_gyroscope,self._log_magnetometer)? ? self._set_up_headers()答案：對于在這里跟進的任何人，事實證明問題在于我使用了 VS Code 調試器，該調試器顯然不適用于多處理，并且以某種方式阻止了生成的進程的成功。
1 回答
叮當貓咪
TA貢獻1776條經驗 獲得超12個贊
我可以在您的代碼中看到一些錯誤：
首先 stop_value == 0 不會像 multiprocess.Value('i', 0) != 0 那樣工作，將該行更改為
while stop_value.value == 0
其次，你永遠不會更新 previous_read_time 所以它會盡可能快地寫入讀數，你會很快用完磁盤
第三，嘗試使用 time.sleep() 你正在做的事情被稱為忙循環，它很糟糕，它不必要地浪費了 CPU 周期。
四，以 self._stop_value = 1 終止可能不會起作用，必須有其他方法來設置該值，也許 self._stop_value.value = 1。
好吧，這是基于您提供的代碼的示例代碼，該代碼工作正常：
import csv
import multiprocessing
import time
from datetime import datetime, timedelta
from random import randint
class IMU(object):
@staticmethod
def read_accelerometer_values():
return dict(x=randint(0, 100), y=randint(0, 100), z=randint(0, 10))
class Foo(object):
def __init__(self, output_filename):
self._output_filename = output_filename
self._csv_headers = ['xxxx','y','z']
self._log_accelerometer = True
self.IMU = IMU()
def _record_data(self, frequency, stop_value):
#self._set_up() # Run setup functions for the data collection device and store it in the self.IMU variable
"""Record data function, which takes a recording frequency, in herz, as an input"""
previous_read_time = datetime.now() - timedelta(1, 0, 0)
self._run_underway = True # Note that a run is now going
Period = 1 / frequency # Period, in seconds, of a recording based on the input frequency
print("Writing output data to", self._output_filename)
with open(self._output_filename, 'w', newline='') as outcsv:
self._writer = csv.writer(outcsv)
self._writer.writerow(self._csv_headers) # Write headers to file
while stop_value.value == 0: # While a run continues
if datetime.now() - previous_read_time >= timedelta(0, 1,
0): # If we've waited a period, collect the data; otherwise keep looping
print("run underway value", self._run_underway)
if datetime.now() - previous_read_time >= timedelta(0, Period,
0): # If we've waited a period, collect the data; otherwise keep looping
next_row = []
if self._log_accelerometer:
# Get values in m/s^2
axes = self.IMU.read_accelerometer_values()
next_row += [axes['x'], axes['y'], axes['z']]
previous_read_time = datetime.now()
self._writer.writerow(next_row)
# Close the csv when done
outcsv.close()
def start_recording(self, frequency_in_hz):
# Create recording process
self._stop_value = multiprocessing.Value('i', 0)
self._process = multiprocessing.Process(target=self._record_data, args=(frequency_in_hz, self._stop_value))
# Start recording process
self._process.start()
print(datetime.now().strftime("%H:%M:%S.%f"), "Data logging process spawned")
print("ID of data logging process: {}".format(self._process.pid))
def end_recording(self, terminate_wait=2):
"""Function to end the recording multithread that's been spawned.
Args: terminate_wait: This is the time, in seconds, to wait after attempting to shut down the process before terminating it."""
# Get process id
id = self._process.pid
# Set stop event for process
self._stop_value.value = 1
self._process.join(terminate_wait) # Wait two seconds for the process to terminate
if self._process.is_alive(): # If it's still alive after waiting
self._process.terminate()
print(datetime.now().strftime("%H:%M:%S.%f"), "Process", id, "needed to be terminated.")
else:
print(datetime.now().strftime("%H:%M:%S.%f"), "Process", id, "successfully ended itself.")
if __name__ == '__main__':
foo = Foo('/tmp/foometer.csv')
foo.start_recording(20)
time.sleep(5)
print('Ending recording')
foo.end_recording()
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