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

learn more… | top users | synonyms (5)

0
votes
3answers
214 views

Socket Connecting to Large number of IPs

I have a text file of ~600 CIDR notation IP blocks which, when expanded, amount to ~17.5M IP addresses. I need to socket connect to each one. If it connects, I add it to a "live" list, if it returns ...
0
votes
5answers
267 views

Race conditions in JVM languages versus C/C++

I was thinking about thread synchronization issues in compiled languages like C++, versus synchronization issues in languages like Java. I'm wondering how a JVM language like Java doesn't (at least ...
1
vote
1answer
250 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 ...
4
votes
2answers
299 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 < ...
0
votes
1answer
196 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
votes
2answers
349 views

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 ( ...
0
votes
1answer
280 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 ...
4
votes
2answers
742 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, ...
19
votes
3answers
5k views

Why not Green Threads?

Whilst I know questions on this have been covered already (e.g. http://stackoverflow.com/questions/5713142/green-threads-vs-non-green-threads), I don't feel like I've got a satisfactory answer. The ...
35
votes
10answers
10k 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 ...
1
vote
3answers
318 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
vote
1answer
65 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 ...
0
votes
2answers
200 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 ...
2
votes
3answers
317 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 ...
1
vote
0answers
84 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 ...
2
votes
4answers
532 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
197 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 ...
1
vote
1answer
143 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 ...
30
votes
5answers
3k views

Testing multi-threaded race conditions

Reading the comments to this answer, specifically: Just because you can't write a test doesn't mean it's not broken. Undefined behaviour which usually happens to work as expected (C and C++ are ...
0
votes
3answers
348 views

BackgroundWorker starting again in Completed event

I want a background worker to continue running and occasionally update the user interface. My first idea was to use a BackgroundWorker and in its completed event just fire it up again. Is using a ...
0
votes
3answers
193 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 ...
4
votes
1answer
199 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. ...
22
votes
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 ...
5
votes
3answers
825 views

What are the so-called “levels” of understanding multithreading?

I seem to remember reading somewhere some list of 4 "levels" of understanding multithreading. This may have been in a formal publication, or it may have been in an extremely informal context (even ...
0
votes
2answers
85 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 ...
0
votes
10answers
974 views

Why does the instruction “do” require a “while”? [closed]

Since this statement is so common: while (true) (Java) or while (1) (C) or sometimes for (;;) Why is there not a single instruction for this? I could think that an instruction that could do it ...
0
votes
1answer
607 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 ...
21
votes
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
vote
2answers
52 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
263 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 ...
8
votes
2answers
2k 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.
1
vote
1answer
216 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 ...
0
votes
1answer
165 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
votes
4answers
451 views

When creating a library for a simple program, what must I do to protect others from its lack of thread safety?

When creating a library for a simple program, is it more cost effective to make it thread safe or is there a way to detect the program's use in a multithreaded program and ASSERT() or otherwise ...
6
votes
3answers
301 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
votes
0answers
30 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
votes
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
votes
0answers
115 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 ...
0
votes
3answers
131 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 ...
3
votes
0answers
175 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
votes
3answers
304 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
votes
1answer
694 views

Relationship between “Task Parallel Library” and “Task-based Asynchronous Pattern”?

In the context of C#, .NET 4/4.5 used for an application running on a web-server, what is the relationship between "Task Parallel Library" and "Task-based Asynchronous Pattern"? I understand one is ...
0
votes
2answers
118 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 ...
0
votes
2answers
187 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. ...
1
vote
1answer
852 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
735 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
165 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 ...
4
votes
1answer
770 views

What's the current best practice for C multithreading?

I've been a Java (and PHP) developer for most of my life, but will need to use C for my next project. I remember some basic stuff we did back in school with fork, pthread, semaphores, etc. but I'm not ...
0
votes
1answer
349 views

Export to Excel - threading

I am working on an ASP.NET application. One requirement by the users is they are capable of exporting to Excel of some UIs. I have worked on them using the Infragistics library, and I have supplied ...
0
votes
0answers
68 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 ...