49 lines
1.2 KiB
Python
49 lines
1.2 KiB
Python
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'''
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Demonstrates the classic threading problem of multiple threads
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non-atomically modifying a value concurrently by get/add/set.
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Can take two arguments:
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--locked Wrap access in a lock.
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--threads N Create N threads.
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'''
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import os
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if 'KUROKO_TEST_ENV' in os.environ:
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return 0
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import kuroko
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from threading import Thread, Lock
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def __main__():
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# Simple flag argument processing.
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let locked = '--locked' in kuroko.argv
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let threadcount = 10 if '--threads' not in kuroko.argv else (int(kuroko.argv[kuroko.argv.index('--threads')+1]))
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# This also demonstrates threads accessing an upvalue
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# which has not yet been closed in another thread.
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let i = 0
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let lock = Lock()
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class Incrementer(Thread):
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def run():
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for c in range(1000):
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if locked:
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with lock:
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i += 1
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else:
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i += 1
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let threads = [Incrementer() for j in range(threadcount)]
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for thread in threads: thread.start()
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for thread in threads: thread.join()
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# Should be 1000 * threadcount - but is it? Almost definitely not without a lock!
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print(i)
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return 0
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if __name__ == '__main__':
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return __main__()
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