Python - multithreading / multiprocessing, very strange problem.
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by orokusaki
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Published on 2010-04-14T21:12:59Z
Indexed on
2010/04/14
21:13 UTC
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Hit count: 639
import uuid
import time
import multiprocessing
def sleep_then_write(content):
time.sleep(5)
print(content)
if __name__ == '__main__':
for i in range(15):
p = multiprocessing.Process(target=sleep_then_write,
args=('Hello World',))
p.start()
print('Ah, what a hard day of threading...')
This script output the following:
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
AAh, what a hard day of threading..
h, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Ah, what a hard day of threading...
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Hello World
Firstly, why the heck did it print the bottom statement sixteen times (one for each process) instead of just the one time?
Second, notice the AAh, and h, about half way down; that was the real output. This makes me wary of using threads ever, now.
(Windows XP, Python 2.6.4, Core 2 Duo)
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