import unittest
from threading import Thread, Barrier
from test.support import threading_helper
import numpy as np

threading_helper.requires_working_threading(module=True)

class ItertoolsThreading(unittest.TestCase):

    
    @threading_helper.reap_threads
    def test_result_type(self):
        number_of_threads = 6
        number_of_iterations = 25
        number_of_cycles = 800

        barrier = Barrier(number_of_threads)
        
        x = np.array([1., 2., 3., 4.], np.dtype([('f1', [('f1', '<i2')])]))
        y = np.array([1, 2,], np.dtype([('f1', [('f1', '<i2')])]))
        
        def work(it):
            barrier.wait()
            for _ in range(number_of_cycles):
                #print(f'{it=} {_}')
                x.dtype = np.dtype([('f1', [('f1', '<i2')])]) # single reference
                y.dtype = np.dtype([('f1', [('f1', '<i2')])]) # single reference
                np.result_type(x, y)
               
               

        for it in range(number_of_iterations):
            print(f'iteration {it}')
            worker_threads = []
            for ii in range(number_of_threads):
                worker_threads.append(
                    Thread(target=work, args=[ii]))

            with threading_helper.start_threads(worker_threads):
                pass

            barrier.reset()

        print('done')

if __name__ == "__main__":
    unittest.main()