Python 中的实时中断
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Real-time interrupts in Python
提问by Stack Player
I have a Python 2.7 program running an infinite while loop and I want to incorporate a timer interrupt. What I aim to do is to set off a timer at some point in the loop, and when 5 seconds have elapsed I want the code to branch to a specific part of the while loop.
我有一个运行无限 while 循环的 Python 2.7 程序，我想合并一个计时器中断。我的目标是在循环中的某个点启动一个计时器，当 5 秒过去后，我希望代码分支到 while 循环的特定部分。
What I have been doing so far is the following: in each iteration of the while loop I am checking how much time has elapsed when I reach that point in the code using
到目前为止，我一直在做的是：在 while 循环的每次迭代中，我使用
time.clock()
and if the difference exceeds 5 I run the chunk of code I mean to run
如果差异超过 5 我运行我的意思是运行的代码块
However that way 7 seconds might pass before I evaluate the time, it will be >5sec but I want to go there exactlywhen 5 seconds pass
但是，在我评估时间之前可能会过去 7 秒，它将 > 5 秒，但我想在 5 秒过去时准确地去那里
Also, I need this to work for more than 1 counter (possibly up to a 100) but I do not want the interrupts to interrupt each other. Using Timer did not work either.
此外，我需要它为 1 个以上的计数器（可能高达 100）工作，但我不希望中断相互中断。使用计时器也不起作用。
I know this can be done using timer interrupts in assembly but how can I do that in python?
我知道这可以在汇编中使用定时器中断来完成，但我如何在 python 中做到这一点？
采纳答案by Roberto Reale
If a single event is to be handled, then the easiest way is to use the signalframework which is a standard module of Python.
如果要处理单个事件，那么最简单的方法是使用signal框架，它是Python的标准模块。
However, if we need a fully-fledged scheduler, then we have to resort to another module: sched. Hereis a pointer to the official documentation. Please be aware, though, that in multi-threaded environments schedhas limitations with respect to thread-safety.
然而，如果我们需要一个成熟的调度器，那么我们必须求助于另一个模块：sched. 这是指向官方文档的指针。但请注意，在多线程环境sched中，线程安全有限制。
Another option is the Advanced Python Scheduler, which is not part of the standard distribution.
另一种选择是Advanced Python Scheduler，它不是标准发行版的一部分。
回答by jfs
You can't get real-timewithout special hardware/software support. You don't need it in most cases (do you need to control giant robots?).
如果没有特殊的硬件/软件支持，您将无法获得实时。大多数情况下你不需要它（你需要控制巨型机器人吗？）。
How to delay several function calls by known numbers of seconds depends on your needs e.g., if a time it takes to run a function is negligible compared to the delay between the calls then you could run all functions in a single thread:
如何将多个函数调用延迟已知秒数取决于您的需要，例如，如果与调用之间的延迟相比，运行函数所需的时间可以忽略不计，那么您可以在单个线程中运行所有函数：
#!/usr/bin/env python
from __future__ import print_function
from Tkinter import Tk
root = Tk()
root.withdraw() # don't show the GUI window
root.after(1000, print, 'foo') # print foo in a second
root.after(0, print, 'bar') # print bar in a jiffy
root.after(2000, root.destroy) # exit mainloop in 2 seconds
root.mainloop()
print("done")
It implements yours "I do not want the interrupts to interrupt each other either"because the next callback is not called until the previous one is complete.
它实现了您的“我也不希望中断相互中断”，因为在前一个回调完成之前不会调用下一个回调。
