If you are relying on an implementation of Python that has a Global Interpreter Lock (ie CPython) and writing multithreaded code, do you really need locks at all? If the GIL doesn't allow multiple instructions to be executed in parallel, wouldn't shared data be unnecessary to protect? sorry if this is a dumb question, but it is something I have always wondered about Python on multi-pr
如果您依赖的是具有Global Interpreter Lock（即CPython）并编写多线程代码的Python实现，那么您是否真的需要锁？ 如果GIL不允许并行执行多条指令，那么不需要共享数据来保护？ 对不起，如果这是一个愚蠢的问题，但这是我一直想在多处理器/核心机器上使用Python的东西。 同样的事情将适用于任何其他具有GIL的语言实现。 如果您在线程之间共享状态，您仍然需要锁定。 GIL只在内部保护口译员。 你自己的代码中仍然可能有
A discussion with a friend led to the following realization: >>> import dis >>> i = lambda n: n*24*60*60 >>> dis.dis(i) 1 0 LOAD_FAST 0 (n) 3 LOAD_CONST 1 (24) 6 BINARY_MULTIPLY 7 LOAD_CONST 2 (60) 10 BINARY_MULTIPLY 11 LOAD_CONST 2 (
与朋友的讨论导致了以下认识： >>> import dis >>> i = lambda n: n*24*60*60 >>> dis.dis(i) 1 0 LOAD_FAST 0 (n) 3 LOAD_CONST 1 (24) 6 BINARY_MULTIPLY 7 LOAD_CONST 2 (60) 10 BINARY_MULTIPLY 11 LOAD_CONST 2 (60) 14 BINARY_MULTI
This question already has an answer here: Speed of calculating powers (in python) 6 answers As per this answer, it's because the implementation of exponentiation has some overhead that multiplication does not. However, naive multiplication will get slower and slower as the exponent increases. An empirical demonstration: In [3]: x = np.random.rand(1e6) In [15]: %timeit x**2 100 loop
这个问题在这里已经有了答案： 计算能力的速度（用python）6个答案 按照这个答案，这是因为幂运算的实现有一些乘法运算没有的开销。 然而，随着指数的增加，初始乘法会变得越来越慢。 经验证明： In [3]: x = np.random.rand(1e6) In [15]: %timeit x**2 100 loops, best of 3: 11.9 ms per loop In [16]: %timeit x*x 100 loops, best of 3: 12.7 ms per loop In [17]: %timeit x**3 10 loops, best of 3: 132
Hi! I'm making a chess engine and I have some problems with the make/ unmake methods. I have a Piece class that holds the type (pawn, queen, etc..) and position of the piece and a Move class that holds the target square, the moved piece and captured piece. The problem is that, when I call the makeMove method, it changes the piece's position to target square inside the Piece object.
嗨！ 我正在制作一个象棋引擎，并且在make / unmake方法中遇到了一些问题。 我有一个Piece类，它保存着棋子的类型（典当，皇后等等）和位置，以及一个Move类，它包含目标方块，被移动的棋子和被捕获的棋子。 问题是，当我调用makeMove方法时，它将片段的位置更改为Piece对象内的方形目标。 但是现在，我无法用Move对象调用unmakeMove，因为现在我没有关于移动来自哪里的信息，因为我刚刚更改了该部分的位置。 你将如何解
In python, I have made a function to make a directory if does not already exist. def make_directory_if_not_exists(path): try: os.makedirs(path) break except OSError as exception: if exception.errno != errno.EEXIST: raise On Windows, sometimes I will get the following exception: WindowsError: [Error 5] Access is denied: 'C:\...\my_path'
在python中，我创建了一个函数来创建一个不存在的目录。 def make_directory_if_not_exists(path): try: os.makedirs(path) break except OSError as exception: if exception.errno != errno.EEXIST: raise 在Windows上，有时我会得到以下异常： WindowsError: [Error 5] Access is denied: 'C:\...\my_path' 它似乎发生在Windows文件浏览器中打开目录时，但我
I'm using Selenium WebDriver with the Chrome driver on OS X, implementing in Python. I'm trying to write a test that verifies if a variety of HTML elements are completely on the screen (for example, I have a tag cloud, and because of my poor implementation, sometimes some of the words slip off the edges of the browser window, so they are half-visible). driver.find_element_by_css_selec
我在OS X上使用Selenium WebDriver和Chrome驱动程序，并使用Python实现。 我试图编写一个测试来验证各种HTML元素是否完全在屏幕上（例如，我有一个标签云，并且由于我的实现不佳，有时候某些单词从浏览器的边缘滑落窗口，所以它们是半透明的）。 driver.find_element_by_css_selector("div.someclass").is_displayed() ，这是我可以在其他地方找到的唯一解决方案，似乎并不奏效; 即使元素部分可见，也会返回True
I want to use os.mkfifo for simple communication between programs. I have a problem with reading from the fifo in a loop. Consider this toy example, where I have a reader and a writer working with the fifo. I want to be able to run the reader in a loop to read everything that enters the fifo. # reader.py import os import atexit FIFO = 'json.fifo' @atexit.register def cleanup(): try:
我想使用os.mkfifo进行程序之间的简单通信。 我在循环中读取fifo时遇到问题。 考虑一下这个玩具的例子，我有一个读者和一个使用fifo的作家。 我希望能够在循环中运行读取器来读取进入fifo的所有内容。 # reader.py import os import atexit FIFO = 'json.fifo' @atexit.register def cleanup(): try: os.unlink(FIFO) except: pass def main(): os.mkfifo(FIFO) with open(FIFO) as fifo
I have this Python application that gets stuck from time to time and I can't find out where. Is there any way to signal Python interpreter to show you the exact code that's running? Some kind of on-the-fly stacktrace? Related questions: Print current call stack from a method in Python code Check what a running process is doing: print stack trace of an uninstrumented Python progr
我有这个不时被卡住的Python应用程序，我找不到在哪里。 有什么方法可以告诉Python解释器向您显示正在运行的确切代码吗？ 某种即时堆栈跟踪？ 相关问题： 从Python代码中的方法打印当前调用堆栈 检查一个正在运行的进程在做什么：打印一个未经修补的Python程序的堆栈跟踪 我有这样的情况下使用的模块 - 一个进程将会运行很长时间，但有时会出现未知和不可重复的原因。 它有点怪异，只适用于unix（需要信号）： impo
I've recently taken an interest in graphics programming and I'm trying to start out by making a simple cube using PyOpenGL and PyGame. I've managed to get it rotating but I can't get consecutive rotations working correctly. I have a simple cube in space and I want to rotate it on global x and y axes using arrow keys (and eventually with a mouse). However, all rotations I'v
我最近对图形编程感兴趣，并试图通过使用PyOpenGL和PyGame制作一个简单的多维数据集来开始。 我已经设法让它旋转，但我无法正确连续旋转。 我在空间中有一个简单的立方体，我想使用箭头键（最终使用鼠标）在全局x和y轴上旋转它。 然而，我试图应用于立方体的所有旋转都会在局部x和y轴上相对于立方体的方向旋转它，而不是关于观察者的视角的全局坐标轴。 我尝试的第一件事是使用glRotatef，但当然导致了局部旋转。 环顾四
I'd like to quickly fill with as few copies as possible a long array of structs that I'm receiving incrementally from C. If my struct is only primary data types, like the following: cdef packed struct oh_hi: int lucky char unlucky Then the following works fine: DEF MAXPOWER = 1000000 cdef oh_hi * hi2u = <oh_hi *>malloc(sizeof(oh_hi)*MAXPOWER) cdef oh_hi [:] hi2me
我想快速填写尽可能少的副本，我从C中逐渐收到一长串结构。 如果我的结构只是主数据类型，如下所示： cdef packed struct oh_hi: int lucky char unlucky 然后，以下工作正常： DEF MAXPOWER = 1000000 cdef oh_hi * hi2u = <oh_hi *>malloc(sizeof(oh_hi)*MAXPOWER) cdef oh_hi [:] hi2me = <oh_hi[:MAXPOWER]> hi2u 但是，一旦我改变我的结构来保存一个字符数组： cdef packed struct oh_hi: