issue 120040.py

import threading
import time
import random

def copy_row(row):
    return [float(value+0.0) for value in row]

def copy_matrix(matrix):
    return [copy_row(row) for row in matrix]


def multiply_row(A, B, row_index, result):
    # Compute the row result
    num_columns_B = len(B[0])
    num_columns_A = len(A[0])
    for j in range(num_columns_B):
        sum = 0
        for k in range(num_columns_A):
            sum += A[row_index][k] * B[k][j]
        result.append(sum)

def parallel_matrix_multiplication(a, b, result, row_indices):
    a = copy_matrix(a)
    b = copy_matrix(b)
    for row_index in row_indices:
        tmp_result = []
        multiply_row(a, b, row_index, tmp_result)
        result[row_index] = tmp_result

def multi_threaded_matrix_multiplication(a, b, num_threads):
    num_rows = len(a)
    result = [[0] * len(b[0]) for _ in range(num_rows)]
    row_chunk = num_rows // num_threads

    threads = []
    for i in range(num_threads):
        start_row = i * row_chunk
        end_row = (i + 1) * row_chunk if i != num_threads - 1 else num_rows
        thread = threading.Thread(target=parallel_matrix_multiplication, args=(a, b, result, range(start_row, end_row)))
        threads.append(thread)
        thread.start()

    for thread in threads:
        thread.join()

    return result

# Helper function to create a random matrix
def create_random_matrix(rows, cols):
    return [[random.random() for _ in range(cols)] for _ in range(rows)]

def main():
    size = 500  # Define matrix size
    a = create_random_matrix(size, size)
    b = create_random_matrix(size, size)
    num_threads = 8  # Define number of threads

    start = time.perf_counter()
    
    result = multi_threaded_matrix_multiplication(a, b, num_threads)
    print("Matrix multiplication completed.", time.perf_counter() - start, "seconds.")

if __name__ == "__main__":
    main()