Updating a list with multiprocessing

[bRitch022]

I am writing a program to control a machine, and this machine needs to have a central registry to keep track of all parameters about the machine (Inputs/outputs, configuration values, etc.). I've set up a list of zeros using the numpy library, and I am able to write to this list correctly. The problem, however, is when I attempt to then read that same list from another process or directly from my main code. I have verified that the data is updating to the list by performing a read action directly after writing. But reading from it from another function shows that it has not been changed.

Here is my code:

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#import numpy as np   class Registry(object):     def __init__(self, registry_size=128, register_size=16):         self.registry_size = registry_size         self.register_size = register_size                   self.registry = np.zeros((registry_size, register_size), dtype=int)         self.buff = np.zeros((1,16)) # Buffer for data in/out       def write16_register(self, reg_addr, data):          # Convert data to 16 digit binary and sign extend        data = int(data)                      # Split data into 8 bit MSB and LSB        data_MSB = (data & 0xFF00) >> 8        data_LSB = (data & 0x00FF)                      # Load MSBs to buff        self.buff = format(data_MSB, '08b')                 # Write MSBs to registry        for i in range(0,8,1):            self.registry[reg_addr][i] = self.buff[i]          # Load LSB to buffer        self.buff = format(data_LSB, '08b')          # Write LSB to registry        for i in range(8,16,1):            self.registry[reg_addr][i] = self.buff[i-8]                          print(self.registry[reg_addr]) if __name__ == '__main__':     p1 = multithreading.Process(target=

The final print(self.registry[reg_addr]) successfully prints the written values. However the following does NOT work:

1 2	def read_register(self, reg_addr):    print(self.registry[reg_addr])

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Standby for edited post... For some reason it did not save my edits. The above post is not up to date

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import numpy as np import multiprocessing   class Registry(object):     def __init__(self, registry_size=128, register_size=16):         self.registry_size = registry_size         self.register_size = register_size                   self.registry = np.zeros((registry_size, register_size), dtype=int)         self.buff = np.zeros((1,16)) # Buffer for data in/out           def write16_register(self, reg_addr, data):             # Convert data to 16 digit binary and sign extend             data = int(data)                           # Split data into 8 bit MSB and LSB             data_MSB = (data & 0xFF00) >> 8             data_LSB = (data & 0x00FF)                           # Load MSB             self.buff = format(data_MSB, '08b')               for i in range(0,8,1):                 self.registry[reg_addr][i] = self.buff[i]               # Load LSB             self.buff = format(data_LSB, '08b')               for i in range(8,16,1):                 self.registry[reg_addr][i] = self.buff[i-8]                               print(self.registry[reg_addr])       def read_register(self, reg_addr):       print(self.registry[reg_addr])   if __name__ == '__main__':     Main_Registry = Registry()     p1 = multiprocessing.Process(target=Main_Registry.write16_register, args=(0x00, 0xB594,))     p2 = multiprocessing.Process(target=Main_Registry.read_register, args=(0x00,))               p1.start()     p2.start()           p1.join()     p2.join()

Output:
[1 0 1 1 0 1 0 1 1 0 0 1 0 1 0 0]
[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

As you can see, the print statement inside the write16_register shows that the registry has been written to. But the print statement in read_register shows that it is unchanged and still zeroes.

Does anyone know why I might be running into this issue?

[bRitch022]

This question was not very well formulated, especially with the code edits, and I don't blame anyone for not attempting a reply. I rewrote the question, and found a solution here