multithreading

问题 I have several threads and each thread writes output to stdout. However I want to redirect the ouput of each thread to a separate file independently of each other. What I mean is the following: Thread1 writes every print, every exception and every other ouput into file1.log Thread2 writes every print, every exception and every other ouput into file2.log and so on. So what I'm looking for is to set the stdout for each thread exclusivly. However setting the stdout only works globally mean that

问题 I have read many posts but still unable to differentiate between all these. All i could understand was Task.Run will call the background thread. async- await is asynchronous programming. Does Task.Run means background thread will behave as a blocking thread? Trying to download multiple large images from internet. How should i use these keywords in combination and why? 回答1: When to use Task.Run, when to use async- await and when to use them in combination I have an entire blog series on the

问题 I am confused on the different terms as to their actual differences. What are each of them and what do they actually mean? My IT teacher at school gives us one definition the one day, and another the next, so please can you shed some light for me. Thanks. 回答1: A thread is a sequence of program instructions that are executed by the machine. We call a program multi-threaded when a single execution of the program has more than one thread. Multi-threading can be simulated on a single-processor

问题 I'm trying to write a web scraper using PyQt5 and multithreading so that I can scrap multiple urls in parallel (i'm aware of this : Scrape multiple urls using QWebPage but I really want to write a parallel version and really can't see why it doesn't work) I've written this code : python import sys from PyQt5.QtGui import * from PyQt5.QtWidgets import * from PyQt5.QtCore import * from PyQt5.QtWebEngineWidgets import QWebEnginePage import time urlb = "https://www.google.fr/" class Worker

问题 I am reading "java concurrency in practice", and the author says: "A program that consists entirely of thread-safe classes may not be thread-safe". How is this possible? I don't seem to understand, can someone provide an example? 回答1: An example would be individual methods on a class that are thread safe, but they are not atomic if you invoke more than one. E.g. if (!threadSafeCollection.contains(thing)) { threadSafeCollection.add(thing); } This may yield incorrect results if another thread

问题 The wait() method on an object can be called only in the synchronized context i.e. the current thread must have a lock on the object to invoke the wait() method. Now if a thread T1 has a lock on an object( obj ) and invokes its wait method obj.wait() . How can other threads get lock on this object( obj ) so that they can also call wait, which is already possessed T1 ? 回答1: wait releases the synchronized context. From the documentation: The current thread must own this object's monitor. The

问题 I have to ask again because no one answered my question before (my problem is NOT a duplicate of How to draw a path on an Android canvas with animation?). Please read it carefully and help me, if possible by providing code. The abouve example is unclear for me, and the Path is created on the flow of drawing. This is NOT what I am looking for... I want to draw ONE Path, that already exist in my View class, by drawing its points with time interval, to simulate an animation. How should I modify

问题 I have a console application which uses an external library. The library insists on always being called from the same thread; it locks up otherwise. (I did try running as STA to see if that would fix it - but no, it really insists you have to always use the same thread. My guess is thread-local storage...) Previously the application communicated using a raw TCP connection. However, I recently changed it to use WCF. Now it seems that WCF chooses threads at random to run my code, which results

问题 I have programmed a boost::thread application, where I might have some race conditions. I want to debug this program. Therefore I used the following valgrind tools: halgrind drd unfortunately they have a very false positive rate. So with the really simple program below valgrind --tool=drd complains about 94 errors, where no should be. So with my complex program I get about 15000 errors. So it is really hard to find the actual error. I could reproduce this behavior with the following boost

问题 I know of the non-intuitive process to set the name of a thread under Windows (see "How to set name to a Win32 Thread?"). Is there a way to get the name of the thread? I don't see any Windows API that lets me do this (http://msdn.microsoft.com/en-us/library/windows/desktop/ms684847(v=vs.85).aspx). 回答1: There is no such WinAPI call since there exists no such thing as thread names. If you set a thread name then the debugger of your IDE will store it for you, which makes it easier to debug.