In-order access to shared resource in python3 Multiprocessing

Question

Given the MWE below:

import multiprocessing

def thread_function(shared_resource : dict, val : int) -> None: 

    if val not in shared_resource.keys(): 
        print(f"Value {val} is not in keys!")
        shared_resource[val] = 1

    shared_resource[val] += 1

def main():

    no_of_threads = 5
    manager       = multiprocessing.Manager()
    
    shared_resource = manager.dict()

    values = [1 , 1 , 2 , 1 , 3, 3, 3, 4, 5]

    with multiprocessing.Pool(no_of_threads) as pool:

        pool.starmap(thread_function,
                     [ (shared_resource, val) for val in values], 
                     chunksize=1)

    print(shared_resource)


if __name__ == "__main__": main()

I am having a readers/writers issue that I don't know how to resolve. The dictionary is a shared resource amongst the threads and I wish for the access to it to be atomic i.e., to avoid the scenario where two threads try to write the same value to it. For instance here is an incorrect output:

Value 1 is not in keys!
Value 1 is not in keys! # <-- Nope! 
Value 2 is not in keys!
Value 3 is not in keys!
Value 4 is not in keys!
Value 5 is not in keys!

On the other hand, there is the possibility that the threads will access the resource in the correct order and the output will be the correct one i.e.,

Value 1 is not in keys!
Value 2 is not in keys!
Value 3 is not in keys!
Value 4 is not in keys!
Value 5 is not in keys!
{1: 4, 2: 2, 3: 4, 4: 2, 5: 2}

But how can I avoid such scenarios and always have them behave as expected? Thank you in advance.