Multi-threading related questions including technique, structure, and safety issues.

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2answers
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Java Multithreading and CPU cores [closed]

I have a simple question this time. If I write an java application with 4 Threads ( each thread does different work ), what will be the difference between single-core, dual core and quad core cpu ( ...
4
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2answers
255 views

Is it better to create thread safe subclasses or make the main class thread safe?

Say we have a class that is frequently used in a single-thread context: public class Foo { public List<Bar> Data; public virtual void ChangeData() { for(var i =0; i < ...
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1answer
140 views

I/O bound or CPU-bound

I have a telephony application, there is a windows service(third party product) running on a remote server. The application runs against the server. To connect the server, we have the code. public ...
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2answers
389 views

Would this be a proper use of threading?

After reading various MSDN articles, tutorials, and posts on here I came up with a design for a windows service that I wanted to make sure my threading strategy is proper and won't lead to memory, ...
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0answers
35 views

Visual Studio: How to breakpoint at a yet-unknown location? [migrated]

I'm working on a rather complex, multithreaded app that is not owned by any one person. Out of many MessageBoxes that are correct, there's at least one that needs a different message. I can get to ...
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10answers
8k views

Why should your code not use 100% CPU? [closed]

I'm speaking specifically about a C# .NET 4 program running on Windows XP or higher, but general answers are also acceptable. Assume an already optimized and efficient program. The problem here is ...
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3answers
101 views

Context Switching behavior?

I need to ask a question that have been bugging me for some time now: If I have a single core and one OS thread, this thread will get 100% of the CPU time and all is good. If I have a single core ...
1
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1answer
43 views

How to effectively split jobs into groups for multiprocessing when the job sizes are unknown

With K processor cores, how to optimally split N jobs into groups, with each group to be processed sequentially by one processor core, when the time to process each job is unknown ahead of time and ...
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0answers
98 views

Is this an spurious wakeup or just a funky (non-spurious) race condition? [migrated]

According to wikipedia: "The race conditions that cause spurious wakeups should be considered rare". But when I run this code, it is showing me that spurious wakeup happens quite often. Is this ...
0
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1answer
32 views

Android, using a Fragment to hold/edit complex object, accesible from any Activity

I'll do my best to describe the problem, but I'm still very new to several concepts that I think this problem requires to be solved (namely interfaces and threads). I should preface this by saying ...
0
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2answers
172 views

When is lock not needed in multithreading

I want 500 objects to be processed concurrently using multithreading. These objects will have some initial data before the threads are created. I am creating 5 threads and each thread takes 100 ...
1
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1answer
105 views

Pass Event between Systems in a multi-threaded Entity-Component-System

Is there a way to pass Events between Systems in a multi-threaded Entity-Component-System that realizes the benefits of saving on system resources? I've read a german article about the ...
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0answers
57 views

Using Singletons in JS with workers

I'm building a javascript application that does continuous drawing, but relies on asynchronous scripts in the background which also need to poll for events and write to "global variables". This got me ...
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4answers
499 views

Why aren't we building and using parallel processors *meant* for general computation?

We all know GPUs are much faster than CPUs for a wide range of applications. When someone asks why we are not just programming for GPUs at all, one of the most common answers is that GPUs are not good ...
3
votes
2answers
175 views

Are there alternatives to using an optional type in a multithreaded environment?

I'm making an MPMC queue in C++, and I would like to find out what the best interface for a try_dequeue method would be (I'm not concerned about its implementation). I'd like to provide a method which ...
0
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3answers
132 views

How should be the approach to start thinking about multi thread programming [closed]

I am an experienced java developer.Of now I have started learning multithreading in java.I am able to grasp most of the concepts but still I am unable to visualize applications running on threads.I ...
1
vote
1answer
121 views

Multithreaded Pre/Post Functions

I'm programming an application for an embedded device. We are using an RTOS that supports multi threading. The device is supposed to mimic an older project that was programmed in plain C (without ...
4
votes
1answer
151 views

Error Handling Strategies in Multithreaded Environments

TL;DR What error generating and handling strategies do you use in Multithreaded code intended for use by others and why do you use them? If applicable, state what programming paradigm it's useful for. ...
0
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1answer
74 views

Synchronized access to network industrial equipment

I have an industrial equipment which is controlled by a software. The software connects to it using sockets, and keeps the connection all the time alive, while from time to time sending commands to ...
22
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6answers
4k views

Multithreading: am I doing it wrong?

I'm working on an application that plays music. During playback, often things need to happen on separate threads because they need to happen simultaneously. For example, the notes of a chord need to ...
18
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1answer
1k views

Is there a difference between fibers, coroutines and green threads and if that is so what is it?

Today I was reading several articles on the Internet about fibers, coroutines and green threads, and it seems like these concepts have very much in common, but there are slight differences, especially ...
1
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2answers
45 views

Should I reference a CopyOnWriteArraySet from the Set interface?

There are two ways to use a CopyOnWriteArraySet: // A Set<Object> set = new CopyOnWriteArraySet<>(); and // B CopyOnWriteArraySet<Object> set = new CopyOnWriteArraySet<>(); ...
0
votes
1answer
187 views

How can I set a time limit for a game?

I am learning the multi-threading and timer in C# now. But it seems I can't find a good solution. For example, I would like to see how many addition problems that I can solve within 1 min. I would ...
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1answer
99 views

Should CountDownLatch be used for waiting for an event?

I have a situation here, where I have a loop that loops x amount of times. The value x is determined by the user. Everytime it loops, I want it to wait for a button click before continuing the loop. ...
2
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0answers
145 views

Scheduling a few CPU-intensive tasks

I need to schedule a small number of CPU-intensive tasks to run every so often, reading from shared data and writing to dedicated buffers. I don't necessarily want to roll my own scheduling, but am ...
0
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2answers
63 views

UI Applications and operations in background threads

I am not really sure about what is the best way to deal with operations executed in background threads in an application I am writing. I am writing it in C# and I am following the MVVM design ...
2
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3answers
218 views

Implementation strategies for atomic counter

I basically have a counter variable that is decremented and frequently polled. There are three options to implement that, that I can think of: Number 1: private volatile int count; public void ...
0
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1answer
160 views

Why (most?) retro computer emulators are single threaded?

All real computer hardware works in parallel. So why most emulators of retro systems (like NES) are single threaded (or I'm not right?)? You have main loop and you counting CPU cycles and after ...
5
votes
3answers
240 views

Is it safe to rely on static analysis to “reproduce” concurrency bugs reliably?

I've inherited some Java code which I suspect harbours some concurrency bugs when synchronizing between a thread that queries data and an IO event that updates the same data. I'm trialling a static ...
0
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0answers
29 views

API providing function to be run in a thread vs. thread that runs this function

I'm writing a Python library which exposes a certain event listener interface. The user can register callbacks to handle different types of events. There is also a function which handles the actual ...
20
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4answers
2k views

What prevents a race condition on a lock?

I understand the basics of what data races are, and how locks/mutexes/semaphores help prevent them. But what happens if you have a "race condition" on the lock itself? For example, two different ...
0
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0answers
42 views

Why is sem_post pthread_mutex_lock protected while sem_wait is not?

All the pthread semaphore examples I have seen protect the sem_post call with a pthread_mutex_lock, but the sem_wait is left unprotected! It seems to me that sem_wait also should be protected in some ...
7
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2answers
662 views

Can someone explain in simple terms what is the disruptor pattern?

I would like if you could explain to me in a simple way how does the disruptor patter work. This concept has been elusive to me as of know. Perhaps with your help I could comprehend it.
0
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3answers
114 views

In which object should I implement wait()/notify()?

I'm working in an Android project with multithreading. Basically I have to wait to the server to respond before sending more data. The data sending task is delimited by the flag boolean ...
0
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1answer
136 views

Good approach for hundreds of comsumers and big files

I have several files (nearly 1GB each) with data. Data is a string line. I need to process each of these files with several hundreds of consumers. Each of these consumers does some processing that ...
2
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0answers
117 views

How can I make a universal construction more efficient?

A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted ...
0
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3answers
257 views

What is Atomicity?

I'm really struggling to find a concrete, easy to grasp, explanation of Atomicity. My understanding thus far is that to ensure an operation is atomic you wrap the critical code in a locker. But ...
0
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2answers
182 views

MVC pattern synchronisation

I am facing a problem in synchronizing my model and view threads I have a view which is table. In it, user can select a few rows. I update the view as soon as the user clicks on any row since I don't ...
0
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2answers
159 views

How other thread can show the incremented value unless the 1st thread reaches the return statement?

My code is given below. In the for loop I am getting unexpected output i.e. before completing the execution of for loop by 1st thread the 2nd thread comes in for loop and shows incremented value. ...
0
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2answers
99 views

When one thread out of four is executing first line in run() then at the same time what will remaining three threads do?

I have four thread instances and they are executing run() code given below: public void run (){ System.out.println("1st line :"+Thread.CurrentThread().getName()); System.out.println("2nd line ...
1
vote
1answer
471 views

When should I use ZeroMQ and when should I use Akka?

My understanding of Akka is that it allows you to define groups of mini-threads ("Actors") and then have them communicate with each other (and do work) using events. My understanding of ZeroMQ is ...
1
vote
1answer
402 views

WCF service - best way to accept requests from a client and do background work?

For a project at work, I was tasked to create a WCF service that will receive email messages from client and queue them on a database, while at the same time the service will check the DB every 30 ...
3
votes
1answer
155 views

Can the possibility of a data race be ignored in some cases? (while having concurrent threads) [duplicate]

I am programming a game engine as a hobby project, and I would like to separate physics and drawing into two separate threads. The position vectors of entities are subject to modifications by the ...
0
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0answers
65 views

Primes and multi-threading

I use to compute primes using linear code which took a long time. As I've an 8 cores processor I thought about multi-threading. At first I use to put a huge number of int in a vector then share the ...
0
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1answer
149 views

Using a progress dialog and multi threading

My .NET Windows desktop application creates an HTML report, and has 3 main phases. It may create multiple reports. I show a progress bar so the user knows (estimates) how long it will take (as well ...
0
votes
0answers
369 views

Make a java program use more processors

I am running a program that is supposed to solve a problem with the brute force approach. My computer has a quad-core CPU. When I run the program clearly java uses only one core, because in my ...
0
votes
1answer
108 views

Use of separate threads or singe thread

In my project, on a security system, I was using a socket to get the details of the client and then store it in a database (his IP and port he connected from and service he accessed). I was wondering ...
0
votes
1answer
299 views

Do threads delete themselves?

Let's say I was working on a Swing application. Most of it is run on the EDT using SwingUtilities.invokeLater() inside the main method, because I heard (please correct me if I'm wrong) that that's ...
1
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1answer
66 views

Good strategy to implement a listener processing tasks provided by the database

Let's assume this conceptual scenario: The database is constantly populated with "a ton" of tasks named PleaseSendAnEmail. A scheduler/listener in background is aimed to handle those tasks. Of ...
0
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2answers
84 views

Locking techniques

Delphi RAD libraries implement many thread friendly objects in a way which forces one to declare another object for storing the reference returned by that object's locking method. The object thus ...