以下簡單腳本會間歇性地掛在subprocess.Popen調用上(大約30%的時間)。
除非use_lock = True,然後它永遠不會掛起,導致我相信子進程不是線程安全的! 預期的行爲是腳本在5-6秒內完成。
爲了演示該錯誤,只需運行「python bugProof.py」幾次,直到它掛起。 Ctrl-C退出。你會看到'後Popen'只出現一次或兩次,但不是第三次。是否是subprocess.Popen不是線程安全的?
#!/bin/sh
echo "Calculating factorial (anything that's somewhat compute intensive, this script takes 3 sec on my machine"
ans=1
counter=0
fact=999
while [ $fact -ne $counter ]
do
counter=`expr $counter + 1`
ans=`expr $ans \* $counter`
done
echo "Factorial calculation done"
read -p "Test input (this part is critical for bug to occur): " buf
echo "$buf"
系統信息: Linux的2.6.32-358.123.2.openstack.el6.x86_64#1 SMP週四09月
import subprocess, threading, fcntl, os, time
end_time = time.time()+5
lock = threading.Lock()
use_lock = False
path_to_factorial = os.path.join(os.path.dirname(os.path.realpath(__file__)),'factorial.sh')
def testFunction():
print threading.current_thread().name, '| pre-Popen'
if use_lock: lock.acquire()
p = subprocess.Popen([path_to_factorial], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
if use_lock: lock.release()
print threading.current_thread().name, '| post-Popen'
fcntl.fcntl(p.stdout, fcntl.F_SETFL, os.O_NONBLOCK)
fcntl.fcntl(p.stderr, fcntl.F_SETFL, os.O_NONBLOCK)
while time.time()<end_time:
try: p.stdout.read()
except: pass
try: p.stderr.read()
except: pass
print threading.current_thread().name, '| DONE'
for i in range(3):
threading.Thread(target=testFunction).start()
上述(factorial.sh)引用的外殼腳本26 17:14:58 EDT 2013 x86_64 x86_64 x86_64 GNU/Linux
Python 2.7.3(默認,2013年1月22日,11:34:30)
[GCC 4.4.6 20120305(Red Hat 4.4.6-4) ] on linux2
Putting close_fds = True在Popen調用中也解決了由於某種原因導致的問題。 – Roman
這實際上是我近期在Python中遇到的最令人不快的事情。 Sooo令人沮喪。 –