CODEWITHSUNDEEP
pythonpython-3.xmultithreadingconcurrency
Subham Dutta
Subham Dutta

Reputation: 11

Running the same function multiple times concurrently

So what I want to do is run the same function multiple times simultaneously while getting a result as return and storing it in an array or list. It goes like this:

def base_func(matrix,arg1,arg2):
    result = []
    for row in range(matrix.shape[0]):
        #perform necessary operation on row and return a certain value to store it into result
        x = func(matrix[row],arg1,arg2)
        result.append(x)
    return np.array(result)

I tried using threading in python. My implementation goes:

def base_func(matrix,arg1,arg2):
    result = []
    threads = []
    for row in range(matrix.shape[0]):
        t = threading.Thread(target=func,args=(matrix[row],arg1,arg2,))
        threads.append(t)
        t.start()
    for t in threads:
        res = t.join()
        result.append(res)
    return np.array(result)

This doesn't seem to work and just returns None from the threads.

Upvotes: 1

Views: 924

Answers (1)

thepunitsingh
thepunitsingh

Reputation: 731

From what I read in the documentation of threading.join(), it says:

As join() always returns None, you must call is_alive() after join() to decide whether a timeout happened – if the thread is still alive, the join() call timed out.

You will always get None from these line of your code:

res = t.join()
result.append(res)

This post mentions a similar problem as yours, please follow this for your solution. You might want to use concurrent.futures module as explained in this answer.

Upvotes: 1

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