1
語境量大僵局
我需要運行一個multiprocessing.ThreadPool內multiprocessing.Process。 起初似乎很奇怪，但它是我發現處理segfault的唯一方法，可能會發生，因爲我正在使用C++共享庫。 如果一個段錯誤追加，進程被終止，我可以檢查process.exitcode並處理它。
問題
過了一會兒，當我試圖加入這一進程死鎖追加。
下面是一個簡單的版本，我的代碼：
import sys, time, multiprocessing
from multiprocessing.pool import ThreadPool
def main():
# Launch 8 workers
pool = ThreadPool(8)
it = pool.imap(run, range(500))
while True:
try:
it.next()
except StopIteration:
break
def run(value):
# Each worker launch it own Process
process = multiprocessing.Process(target=run_and_might_segfault, args=(value,))
process.start()
while process.is_alive():
sys.stdout.write('.')
sys.stdout.flush()
time.sleep(0.1)
# Will never join after a while, because of a mystery deadlock
process.join()
# Deals with process.exitcode to log errors
def run_and_might_segfault(value):
# Load a shared library and do stuff (could throw c++ exception, segfault ...)
print(value)
if __name__ == '__main__':
main()
這裏是一個可能的輸出：
➜ ~ python m.py
..0
1
........8
.9
.......10
......11
........12
13
........14
........16
........................................................................................
正如你所看到的，process.is_alive()幾次迭代後常是真實的，過程中會絕不加入。
如果我CTRL-C的腳本得到這個堆棧跟蹤：
Traceback (most recent call last):
File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/multiprocessing/pool.py", line 680, in next
item = self._items.popleft()
IndexError: pop from an empty deque
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "m.py", line 30, in <module>
main()
File "m.py", line 9, in main
it.next()
File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5 /lib/python3.5/multiprocessing/pool.py", line 684, in next
self._cond.wait(timeout)
File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5 /lib/python3.5/threading.py", line 293, in wait
waiter.acquire()
KeyboardInterrupt
Error in atexit._run_exitfuncs:
Traceback (most recent call last):
File "/usr/local/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5 /lib/python3.5/multiprocessing/popen_fork.py", line 29, in poll
pid, sts = os.waitpid(self.pid, flag)
KeyboardInterrupt
PS 在MacOS使用Python 3.5.2。
各種幫助表示感謝，謝謝。
編輯
我嘗試使用Python 2.7版，它運作良好。可能只是一個python 3.5問題？