How do I deep copy lists in Python across multiple processes?

When working with multiple processes in Python, it's often necessary to make deep copies of data structures, such as lists. This ensures that each process has its own independent copy of the data, preventing unexpected modifications. To achieve this, the `copy` module can be utilized, particularly the `deepcopy` function. However, when using multiple processes, especially with the `multiprocessing` module, it's important to note that objects are typically passed by serialization, so use of `deepcopy` is often implicit. Here's a simple example of how to use deep copying with lists in a multiprocessing context.

import multiprocessing import copy def process_function(original_list): # Create a deep copy of the original list list_copy = copy.deepcopy(original_list) # Modify the copy list_copy.append('modified') print(f'List in process: {list_copy}') if __name__ == '__main__': original_list = ['item1', 'item2', 'item3'] print(f'Original List: {original_list}') # Create a new process process = multiprocessing.Process(target=process_function, args=(original_list,)) process.start() process.join() print(f'Original List after process: {original_list}')

deep copy multiprocessing Python lists copy module Python processes

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