concurrency

问题 The question is rather easy, in a way. Suppose I have this class: static class Singleton { } And I want to provide a singleton factory for it. I can do the (probably) obvious. I am not going to mention the enum possibility or any other, as they are of no interest to me. static final class SingletonFactory { private static volatile Singleton singleton; public static Singleton getSingleton() { if (singleton == null) { // volatile read synchronized (SingletonFactory.class) { if (singleton ==

问题 The question is rather easy, in a way. Suppose I have this class: static class Singleton { } And I want to provide a singleton factory for it. I can do the (probably) obvious. I am not going to mention the enum possibility or any other, as they are of no interest to me. static final class SingletonFactory { private static volatile Singleton singleton; public static Singleton getSingleton() { if (singleton == null) { // volatile read synchronized (SingletonFactory.class) { if (singleton ==

问题 The question is rather easy, in a way. Suppose I have this class: static class Singleton { } And I want to provide a singleton factory for it. I can do the (probably) obvious. I am not going to mention the enum possibility or any other, as they are of no interest to me. static final class SingletonFactory { private static volatile Singleton singleton; public static Singleton getSingleton() { if (singleton == null) { // volatile read synchronized (SingletonFactory.class) { if (singleton ==

问题 The question is rather easy, in a way. Suppose I have this class: static class Singleton { } And I want to provide a singleton factory for it. I can do the (probably) obvious. I am not going to mention the enum possibility or any other, as they are of no interest to me. static final class SingletonFactory { private static volatile Singleton singleton; public static Singleton getSingleton() { if (singleton == null) { // volatile read synchronized (SingletonFactory.class) { if (singleton ==

问题 I was reading an article about concurrent programming with c++ (link). In this article, author shows a code that std::async runs two functions with the same thread. Also, when he used std::future with std::async, it acts differently again and runs all functions with independent threads. Why async behave like that and it has this uncontrolled manner? also, How can I develope a real concurrent program with this feature? is that possible at all or I should miss it? 回答1: I suggests to also read

问题 I am trying to append values to a list. But, as it's multiprocessing, the list is ending up with just one value finally. Is there a way where I can append sizes of all the images to the list rather than just one? import cv2 import concurrent.futures import os length = [] def multi_proc(image): name = image[0:-4] im = cv2.imread(image) final_im = cv2.resize(im, (100,100)) cv2.imwrite(name+"rs"+".png", final_im) l = im.shape print(l) length.append(l) with concurrent.futures.ProcessPoolExecutor(

问题 I was reading an article about concurrent programming with c++ (link). In this article, author shows a code that std::async runs two functions with the same thread. Also, when he used std::future with std::async, it acts differently again and runs all functions with independent threads. Why async behave like that and it has this uncontrolled manner? also, How can I develope a real concurrent program with this feature? is that possible at all or I should miss it? 回答1: I suggests to also read

问题 I have the following sidekiq.yml config file, but I'm not sure how to build a separate queue with lower concurrency. How can I do this? --- :concurrency: 25 :pidfile: ./tmp/pids/sidekiq.pid :logfile: ./log/sidekiq.log :queues: - default - [high_priority, 2] - [import_queue, 3] - [user_queue, 4] :daemon: true I would like to do something like the following though, --- :concurrency: 25 :pidfile: ./tmp/pids/sidekiq.pid :logfile: ./log/sidekiq.log :queues: - default - [high_priority, 2] - [import

问题 So my requirement is to read multiple CSV files (each having a minimum of a million rows) and then parse each line. Currently, the way I have broken up my pipeline, I am first creating a separate pipeline to just read a CSV file into a string[] and then I plan to create the parsing pipeline later. But seeing the results of my File Reading Pipeline, I am dumbfounded because it is considerably slower than just looping through the CSV file and then looping through the rows. static public

问题 Inspired by The Little Book of Semaphores, I decided to implement the Producer-Consumer problem using Semaphores. I specifically want to be able to stop all Worker threads at will. I've tested my methodolodgy extensively and can't find anything faulty. Following code is a prototype for testing and can be ran as a Console application: using System; using System.Collections.Concurrent; using System.Threading; using NUnit.Framework; public class ProducerConsumer { private static readonly int