Python 运行时错误：主线程不在主循环中
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RuntimeError: main thread is not in main loop
提问by user2040823
When I call
当我打电话
self.client = ThreadedClient()
in my Python program, I get the error
在我的 Python 程序中，出现错误
"RuntimeError: main thread is not in main loop"
“运行时错误：主线程不在主循环中”
I have already done some googling, but I am making an error somehow ... Can someone please help me out?
我已经做了一些谷歌搜索，但不知何故我犯了一个错误......有人可以帮我吗？
Full error:
完整错误：
Exception in thread Thread-1:
Traceback (most recent call last):
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 530, in __bootstrap_inner
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 483, in run
File "/Users/Wim/Bird Swarm/bird_swarm.py", line 156, in workerGuiThread
self.root.after(200, self.workerGuiThread)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 501, in after
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1098, in _register
RuntimeError: main thread is not in main loop
Classes:
课程：
class ThreadedClient(object):
def __init__(self):
self.queue = Queue.Queue( )
self.gui = GuiPart(self.queue, self.endApplication)
self.root = self.gui.getRoot()
self.running = True
self.GuiThread = threading.Thread(target=self.workerGuiThread)
self.GuiThread.start()
def workerGuiThread(self):
while self.running:
self.root.after(200, self.workerGuiThread)
self.gui.processIncoming( )
def endApplication(self):
self.running = False
def tc_TekenVogel(self,vogel):
self.queue.put(vogel)
class GuiPart(object):
def __init__(self, queue, endCommand):
self.queue = queue
self.root = Tkinter.Tk()
Tkinter.Canvas(self.root,width=g_groottescherm,height=g_groottescherm).pack()
Tkinter.Button(self.root, text="Move 1 tick", command=self.doSomething).pack()
self.vogelcords = {} #register of bird and their corresponding coordinates
def getRoot(self):
return self.root
def doSomething():
pass #button action
def processIncoming(self):
while self.queue.qsize( ):
try:
msg = self.queue.get(0)
try:
vogel = msg
l = vogel.geeflocatie()
if self.vogelcords.has_key(vogel):
cirkel = self.vogelcords[vogel]
self.gcanvas.coords(cirkel,l.geefx()-g_groottevogel,l.geefy()-g_groottevogel,l.geefx()+g_groottevogel,l.geefy()+g_groottevogel)
else:
cirkel = self.gcanvas.create_oval(l.geefx()-g_groottevogel,l.geefy()-g_groottevogel,l.geefx()+g_groottevogel,l.geefy()+g_groottevogel,fill='red',outline='black',width=1)
self.vogelcords[vogel] = cirkel
self.gcanvas.update()
except:
print('Failed, was van het type %' % type(msg))
except Queue.Empty:
pass
回答by abarnert
You're running your main GUI loop in a thread besides the main thread. You cannot do this.
您正在主线程之外的线程中运行主 GUI 循环。你不可以做这个。
The docs mention offhandedly in a few places that Tkinter is not quite thread safe, but as far as I know, never quite come out and say that you can only talk to Tk from the main thread. The reason is that the truth is somewhat complicated. Tkinter itself isthread-safe, but it's hard to use in a multithreaded way. The closest to official documentation on this seems to be this page:
文档在一些地方不经意地提到 Tkinter 不是完全线程安全的，但据我所知，从来没有站出来说你只能从主线程与 Tk 对话。原因是真相有些复杂。Tkinter 本身是线程安全的，但很难以多线程方式使用。最接近官方文档的似乎是这个页面：
Q. Is there an alternative to Tkinter that is thread safe?
Tkinter?
Just run all UI code in the main thread, and let the writers write to a Queue object…
问：是否有线程安全的 Tkinter 替代方案？
特金特？
只需在主线程中运行所有 UI 代码，然后让编写者写入 Queue 对象……
(The sample code given isn't great, but it's enough to figure out what they're suggesting and do things properly.)
（给出的示例代码不是很好，但足以弄清楚他们的建议并正确地做事。）
There actually isa thread-safe alternative to Tkinter, mtTkinter. And its docs actually explain the situation pretty well:
实际上有一个线程安全的替代 Tkinter，mtTkinter。它的文档实际上很好地解释了这种情况：
Although Tkinter is technically thread-safe (assuming Tk is built with --enable-threads), practically speaking there are still problems when used in multithreaded Python applications. The problems stem from the fact that the _tkinter module attempts to gain control of the main thread via a polling technique when processing calls from other threads.
尽管 Tkinter 在技术上是线程安全的（假设 Tk 是使用 --enable-threads 构建的），但实际上在多线程 Python 应用程序中使用时仍然存在问题。问题源于这样一个事实，即 _tkinter 模块在处理来自其他线程的调用时试图通过轮询技术获得对主线程的控制。
I believe this is exactly what you're seeing: your Tkinter code in Thread-1 is trying to peek into the main thread to find the main loop, and it's not there.
我相信这正是您所看到的：您在 Thread-1 中的 Tkinter 代码试图窥视主线程以找到主循环，但它并不存在。
So, here are some options:
所以，这里有一些选择：
- Do what the Tkinter docs recommend and use TkInter from the main thread. Possibly by moving your current main thread code into a worker thread.
- If you're using some other library that wants to take over the main thread (e.g.,
twisted), it may have a way to integrate with Tkinter, in which case you should use that. - Use
mkTkinterto solve the problem.
- 执行 Tkinter 文档的建议并从主线程使用 TkInter。可能通过将您当前的主线程代码移动到工作线程中。
- 如果您正在使用其他一些想要接管主线程的库（例如，
twisted），它可能有一种与 Tkinter 集成的方法，在这种情况下，您应该使用它。 - 使用
mkTkinter来解决这个问题。
Also, while I didn't find any exact duplicates of this question, there are a number of related questions on SO. See this question, this answer, and many more for more information.
另外，虽然我没有发现这个问题的任何完全重复，但有一些关于 SO 的相关问题。请参阅此问题、此答案以及更多信息以获取更多信息。
回答by Christian Mosz
Since all this did help my problem but did not solve it completely here is an additional thing to keep in mind:
由于所有这些确实帮助了我的问题，但并没有完全解决它，因此需要记住的另一件事是：
In my case I started off importing the pyplot library in many threads and using it there. After moving all the library calls to my main thread I still got that error.
就我而言，我开始在许多线程中导入 pyplot 库并在那里使用它。将所有库调用移动到我的主线程后，我仍然遇到该错误。
I did get rid of it by removing all import statements of that library in other files used in other threads. Even if they did not use the library the same error was caused by it.
我确实通过删除其他线程中使用的其他文件中该库的所有导入语句来摆脱它。即使他们没有使用该库，也会导致相同的错误。
回答by CPSuperstore
I know this is late, but I set my thread to a Daemon, and no exception was raised:
我知道这已经晚了，但是我将线程设置为守护进程，并且没有引发异常：
t = threading.Thread(target=your_func)
t.setDaemon(True)
t.start()
回答by dishendra mishra
from tkinter import *
from threading import Thread
from time import sleep
from random import randint
class GUI():
def __init__(self):
self.root = Tk()
self.root.geometry("200x200")
self.btn = Button(self.root,text="lauch")
self.btn.pack(expand=True)
self.btn.config(command=self.action)
def run(self):
self.root.mainloop()
def add(self,string,buffer):
while self.txt:
msg = str(randint(1,100))+string+"\n"
self.txt.insert(END,msg)
sleep(0.5)
def reset_lbl(self):
self.txt = None
self.second.destroy()
def action(self):
self.second = Toplevel()
self.second.geometry("100x100")
self.txt = Text(self.second)
self.txt.pack(expand=True,fill="both")
self.t = Thread(target=self.add,args=("new",None))
self.t.setDaemon(True)
self.t.start()
self.second.protocol("WM_DELETE_WINDOW",self.reset_lbl)
a = GUI()
a.run()
maybe this example would help someone.
也许这个例子会对某人有所帮助。
