如何在Python中跨线程共享全局变量？
我想使用全局变量结束在单独线程中运行的循环。但这段代码似乎并没有停止循环中的线程。我希望程序不再打印“.” 2秒后，但它仍然无限期地运行。
我在这里做的是根本错误的事情吗？
import time
import threading
run = True
def foo():
while run:
print '.',
t1 = threading.Thread(target=foo)
t1.run()
time.sleep(2)
run = False
print 'run=False'
while True:
pass
I want to end a loop running in a separate thread using a global variable. but this code does not seem to stop the thread in loop. I expect the program not to print any more '.' after 2 seconds, but it still runs indefinitely.
Am I doing something fundamentally wrong here?
import time
import threading
run = True
def foo():
while run:
print '.',
t1 = threading.Thread(target=foo)
t1.run()
time.sleep(2)
run = False
print 'run=False'
while True:
pass
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您正在通过调用
t1.run()在主线程上执行foo()。您应该调用t1.start()。您有两个
foo()定义 - 没关系，但不应该在那里。您没有将
sleep()放入线程循环内（在 foo() 中）。这是非常糟糕的，因为它会占用处理器。如果不让它休眠更长时间，您至少应该放置time.sleep(0)（将时间片释放给其他线程）。这是一个工作示例：
You are executing
foo()on the main thread by callingt1.run(). You should callt1.start()instead.You have two definitions of
foo()- doesn't matter, but shouldn't be there.You didn't put a
sleep()inside the thread loop (in foo()). This is very bad, since it hogs the processor. You should at least puttime.sleep(0)(release time slice to other threads) if not make it sleep a little longer.Here's a working example:
您不是通过调用
run()来启动线程，而是通过调用start()来启动它。解决这个问题使它对我有用。
You don't start a thread by calling
run(), you start it by callingstart().Fixing that made it work for me.
除了给出的答案之外......
变量“run”是一个全局变量。
当您在另一个函数中修改它时，例如在 main() 函数中，您必须引用全局变量，否则它将不会被全局修改。
In addition to the answers given ...
The variable 'run' is a global variable.
When you modify it within another function, e.g. within the main() function, you must make reference to the variable being global otherwise it will not be globally modified.