multiprocess | 易学教程

Python, using multiprocess is slower than not using it

阅读更多关于 Python, using multiprocess is slower than not using it

问题 After spending a lot of time trying to wrap my head around multiprocessing I came up with this code which is a benchmark test: Example 1: from multiprocessing import Process class Alter(Process): def __init__(self, word): Process.__init__(self) self.word = word self.word2 = '' def run(self): # Alter string + test processing speed for i in range(80000): self.word2 = self.word2 + self.word if __name__=='__main__': # Send a string to be altered thread1 = Alter('foo') thread2 = Alter('bar')

python进程

阅读更多关于 python进程

【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 进程是计算机中的程序关于某数据集合上的一次运行活动，是系统进行资源分配和调度的基本单位，是操作系统结构的基础。在早期面向进程设计的计算机结构中，进程是程序的基本执行实体；在当代面向线程设计的计算机结构中，进程是线程的容器。程序是指令、数据及其组织形式的描述，进程是程序的实体。狭义定义：进程是正在运行的程序的实例（an instance of a computer program that is being executed）。广义定义：进程是一个具有一定独立功能的程序关于某个数据集合的一次运行活动。它是操作系统动态执行的基本单元，在传统的操作系统中，进程既是基本的分配单元，也是基本的执行单元。进程概念进程是一个实体。每一个进程都有它自己的地址空间，一般情况下，包括文本区域（text region）、数据区域（data region）和堆栈（stack region）。文本区域存储处理器执行的代码；数据区域存储变量和进程执行期间使用的动态分配的内存；堆栈区域存储着活动过程调用的指令和本地变量。进程是一个“执行中的程序”。程序是一个没有生命的实体，只有处理器赋予程序生命时（操作系统执行之），它才能成为一个活动的实体，我们称其为进程。进程是操作系统中最基本、重要的概念。是多道程序系统出现后

How to manage scope using multiprocessing

阅读更多关于 How to manage scope using multiprocessing

问题 I'm trying to implement a function that uses python multiprocessing in order to speed-up a calculation. I'm trying to create a pairwise distance matrix but the implementation with for loops takes more than 8 hours. This code seems to work faster but when I print the matrix is full of zeros. When I print the rows in the function it seems to work. I think is a scope problem but I cannot understand how to deal with it. import multiprocessing import time import numpy as np def MultiProcessedFunc

CreateFileMapping, MapViewOfFile, handle leaking c++

阅读更多关于 CreateFileMapping, MapViewOfFile, handle leaking c++

问题 Background: I am trying to create a memory mapped file that can be accessed by multiple processes. In the below code I only put in the code that pertains to the question I currently have to make things simpler. According to msdn I should be able to create a filemap, map the view of the file and close the handle I received from CreateFileMapping and the MapViewOfFile will keep my FileMap alive. The FileMap should be still accessible until I UnmapViewOfFile. MSDN: CreateFileMapping function

Killing all threads and the process from a thread of the same process

阅读更多关于 Killing all threads and the process from a thread of the same process

问题 I have a process which spawns 2 types of thread classes. One thread is responsible for consuming a job_queue (100Threads of this class are usually running). And second thread is a killing thread. I am using a result_done flag which is being set from thread2 and the issue is my threads1 wait for X seconds and then check if result_done flag is set. def run(self): while True: try: val = self.job_queue.get(True,self.maxtimeout) except: pass if self.result_done.isset(): return Now, if maxtimeout

pathos cpickle error on python 2.7.13/14 using windows 10

阅读更多关于 pathos cpickle error on python 2.7.13/14 using windows 10

问题 Based on the example multiprocess using pathos and dill I hit the wall of cPickle errors. I did as www3cam did; with a little addition.. by removing pathos, dill, multiprocess and pyreadline. Then hit pip install pathos --no-cache-dir after carefully removed those side-packages mentioned above. Fresh install, cold-reboot of PC and an Anacoda2 update later... the jar with cPickles... is still there and Frank Zappa keeps singing his "Titties and Beer" song. The modified code from 1: #!/usr/bin

How can I send messages (or signals) from a parent process to a child process and viceversa in Perl?

阅读更多关于 How can I send messages (or signals) from a parent process to a child process and viceversa in Perl?

问题 Im writing a program that manage muti-processes. This is what I have done and its working great! but now, I want to send messages from the child processes to the parent process and viceversa (from the parent to the childs), do you know the best way? Do you know if what I have done is the proper way for what I want (send messages, or signals or share memory from the child processes to the parent process and viceversa)? Thanks in advance!! #!/usr/bin/perl -w use strict; use warnings; main(@ARGV

C++ how to check if file is in use - multi-threaded multi-process system

阅读更多关于 C++ how to check if file is in use - multi-threaded multi-process system

问题 C++: Is there a way to check if a file has been opened for writing by another process/ class/ device ? I am trying to read files from a folder that may be accessed by other processes for writing. If I read a file that is simultaneously being written on, both the read and the write process give me errors (the writing is incomplete, I might only get a header). So I must check for some type of condition before I decide whether to open that specific file. I have been using boost::filesystem to

One Android application's activity running in the process of another; what does `android:multiprocess` do?

阅读更多关于 One Android application's activity running in the process of another; what does `android:multiprocess` do?

问题 Big picture I have two Android application, Host and Guest . I am trying to run an activity from Guest such that it immediately opens an activity in Host . The intention is that launching the Guest app should run in the Host , but appear to be running as the Guest (i.e. the user should, to all intents and purposes, not know of the host's existence despite it doing the heavy lifting for the guest). This question is about getting that Host activity to run in the process belonging to Host . (

Python Process blocked by urllib2

阅读更多关于 Python Process blocked by urllib2

问题 I set up a process that read a queue for incoming urls to download but when urllib2 open a connection the system hangs. import urllib2, multiprocessing from threading import Thread from Queue import Queue from multiprocessing import Queue as ProcessQueue, Process def download(url): """Download a page from an url. url [str]: url to get. return [unicode]: page downloaded. """ if settings.DEBUG: print u'Downloading %s' % url request = urllib2.Request(url) response = urllib2.urlopen(request)