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

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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 ...
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1answer
590 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 ...
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2answers
104 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 ...
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2answers
168 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. ...
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1answer
564 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 ...
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1answer
476 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 ...
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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 ...
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1answer
737 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 ...
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1answer
286 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 ...
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0answers
66 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 ...
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4answers
1k views

Should multi-threading be used for tasks which does not involve IO operation?

I was reading a book on OS and got confused between different terminologies. I hope i will get my doubt cleared here. These questions might be very basic for some experts, but i find this platform ...
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1answer
161 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 ...
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0answers
406 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 ...
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5answers
2k views

Does immutability entirely eliminate the need for locks in multi-processor programming?

Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to ...
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1answer
110 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 ...
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1answer
568 views

Running a process multiple times at the same time

I have a c++ program with opencv library which takes an image as input and perform pose estimation,color detection,phog. When I run this program from the command line it takes around 4-5sec to ...
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1answer
69 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 ...
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4answers
5k views

Problems of multiple threads sharing/accessing the same data [closed]

I have been researching into when data is being accessed or shared by multiple threads within Java. And looking into the problems such as: Thread Interference Memory Consistency Deadlock Starvation ...
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2answers
91 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 ...
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1answer
31 views

Difference between TSimpleRWSync's BeginWrite and BeginRead methods?

I have recently switched to TSimpleRWSync from TRTLCriticalSection. The methods BeginRead and BeginWrite confuse me as wherever I read help, they seemingly do the same thing i.e. acquire the critical ...
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2answers
160 views

Emulating communication between Android and microcontroller using threads or services or… other?

I am not sure what is the best way for the tasks below: threads, AsyncTasks, Loopers, services? Why? Are there other candidates? I need threads/Tasks/Services/other for: Plotting data, (refreshing ...
17
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4answers
3k views

Programs that claim they are not “multi-core” friendly

You see this phrase or similar kicked around from time to time, generally referring to a program that claims they were not designed to take full advantage of multi-core processors. This is common ...
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0answers
18 views

Threading and async intterupting on same process and thread, along with related

So, I'm trying to understand threads. I realize they are a mix of hardware and OS decisions. I also know that a thread, or process, has a set of register/stack variables and functions. In each thread, ...
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4answers
496 views

How to convince my teammates that spawning numerous threads is a bad design? [closed]

I've stumbled upon this problem when tried to run our application in bad network conditions; it spawns hundreds of threads (which exist long time before termination), and with time the application ...
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3answers
206 views

Is it possible to perform mutual exclusion of threads without OS support?

I suppose you could adapt distributed mutual exclusion algorithms (Ricart/Agrawala, etc), but aside from these more exotic approaches, are you required to use primitives provided by the OS in order to ...
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1answer
116 views

Non-Recursive vs Recursive Locks?

I am thinking of using non-recursive locks; I have found them to be having performance superiority over the standard recursive locks (e.g. SimpleRWSync). I have mainly been using critical sections but ...
2
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2answers
298 views

Should I lock a list of objects while a socket is receiving messages?

I have a scenario where I will be receiving messages through a socket connection. I also need to keep a list of 100 messages (such as List) and periodically toss out old messages from the list when a ...
3
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2answers
620 views

Thread safe GUI programming

I have been programming Java with swing for a couple of years now, and always accepted that GUI interactions had to happen on the Event Dispatch Thread. I recently started to use GTK+ for C ...
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6answers
449 views

Why are threads called threads?

I understand that a process a unit of resource ownership and executable instructions. Threads allow a process to share its resources with multiple executions, and it's easier for an OS to schedule ...
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0answers
191 views

Managing child worker thread list

After so much research, I thought I should ask the experts. I am working on a project for my corporate employer, we have android and iPhone mobile apps that make request to a web service, the request ...
3
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1answer
126 views

Do you have to ban atomics to get good tool support for race detectors?

It seems that Helgrind treats atomics the same way as normal read/write operations. So, using atomics will result in lots of false positives. I don't know exactly how ThreadSanitizer deals with ...
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1answer
230 views

Extracting data from log files

I will be extracting certain bits from log files using regular expressions to filter out bit of data. Initially I was going to do this with Python. I later started to think about the fastest way I can ...
4
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1answer
733 views

Design patterns for multi-threaded messaging server

I'm designing an instant messaging server as a personal exercise to improve my understanding and application of multi-threading and design patterns in Java. I'm still designing, there's no code yet. ...
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4answers
2k views

Threads or ThreadPool? Fixed or Dynamic ThreadPool?

I have a java program which listens on a port for input. Based on Input, it calls a webservice and then returns a success/failure back to the client program. I fork a thread for each client ...
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0answers
564 views

Best method for async initialization of view model in MVVM pattern (WPF)

I'm working on a business application (C#, WPF, EF, MVVM). I need to load a bunch of items from database, create view models for them and put them in a window. Is there a way to create the view model ...
10
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1answer
2k views

Are go-langs goroutine pools just green threads?

The commentator here offers the following criticism of green threads: I was initially sold on the N:M model as a means of having event driven programming without the callback hell. You can write ...
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1answer
129 views

Optimising news fetching

I have a web scraper for scraping news from different sources in wp7. My current appraoch for doing this is: load newspapers information from xml file. go to the specified sections and fetch the ...
25
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8answers
3k views

When would you need “hundreds of thousands” of threads?

Erlang, Go, and Rust all claim in one way or another that they support concurrent programming with cheap "threads"/coroutines. The Go FAQ states: It is practical to create hundreds of thousands ...
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0answers
106 views

Why user threads are mapped to Kernel threads

Since user threads are mapped to kernel threads, why don't we create all threads as kernel threads that is a process with zero user thread. Doesn't mapping of user thread to kernel thread create ...
3
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1answer
1k views

Database design/relationship for threading messages

What's the database design or business logic for creating an app for messaging between users? I am having difficulties with choosing how to approach the relationship between each Conversation of User ...
2
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1answer
253 views

Transactional Memory vs Mutex and Locks

Just found out that Intel processors now have Transactional Memory support !!!! I learned about Transactional operations in my dB/OS class, it is a very simple concept: entire operation is executed or ...
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6answers
1k views

Why don't xUnit frameworks allow tests to run in parallel?

Do you know of any xUnit framework that allows to run tests in parallel, to make use of multiple cores in today's machine? If none (or so few) of them does it, maybe there is a reason... Is it that ...
2
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2answers
2k views

How Stack and Heap is allocated for threads under the same process in Windows?

Stack for different thread is different.but what about Heap. If Heap is different for different threads, then how they share objects?
10
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2answers
668 views

Is my description of the actor model right?

If I understood, the actor model is just like the object model, but with a few differences: EVERY object spawns it's own separate thread and its not a problem even when you have thousands of ...
15
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1answer
768 views

How can I tell if I am overusing multi-threading?

I currently feel like I am over-using multi-threading. I have 3 types of data, A, B and C. Each A can be converted to multiple Bs and each B can be converted to multiple Cs. I am only interested in ...
3
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2answers
5k views

JUnit Testing in Multithread Application

This is a problem me and my team faces in almost all of the projects. Testing certain parts of the application with JUnit is not easy and you need to start early and to stick to it, but that's not the ...
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2answers
177 views

Why would Java app make RPC call to itself?

I am working with a multithreaded homegrown multi-module app in my new job. We use the the Thrift protocol to communicate RPC calls between different stand-alone applications in a distributed system. ...
14
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3answers
8k views

UML Diagrams of Multi-Threaded Applications

For single-threaded applications I like to use class diagrams to get an overview of the architecture of that application. This type of diagram, however, hasn’t been very helpful when trying to ...
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0answers
128 views

Alternatives to Pessimistic Locking in Cluster Applications

I am researching alternatives to database-level pessimistic locking to achieve transaction isolation in a cluster of Java applications going against the same database. Synchronizing concurrent access ...
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2answers
5k views

How is multi-threading different in a Java based Web Application vs Stand-alone Java Application

I am fairly new to Java and my experience is limited to Web Based Applications running on a Web Container (Jboss in my case). Am I correct in saying that for Web Applications the web container takes ...