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

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3
votes
1answer
54 views

Is there use case for implementing a callback if a future is returned?

If I have function which returns a future, is there any reason to also include a callback where the callback is simply called right before the future completes? The only advantage I can think of ...
0
votes
1answer
51 views

Taskrunner - with multi threading design [on hold]

I am looking for advice on how to implement a multi threaded task runner. My background is Java and Spring. It would look like the following. BatchTask Each BatchTask shall run in parallel and ...
2
votes
6answers
212 views

How does immutability remove the need for locks when two threads are trying to update the shared state?

Okay so I read through this: Does immutability entirely eliminate the need for locks in multi-processor programming? And this was the main takeaway for me: Now, what does it get you? ...
1
vote
3answers
301 views

Do I have to fork a server program as an “C” child process in order for correct interprocess communication to take place?

I would like to implement interprocess communication between an Ubuntu Linux 15.10 mono 4.1.2 C# recorder client and Ubuntu Linux 15.10 mono 4.1.2 C# video server using a C++ mutex class and C++ ...
2
votes
1answer
53 views

How to design a dynamic thread allocator

Forgive the title if it isn't correct, I am just not sure what I am trying to design is called. Say I have a number of tasks I want to run, N. Additionally, I have a maximum number of threads I can ...
45
votes
8answers
6k views

What are the drawbacks of making a multi-threaded JavaScript runtime implementation? [closed]

I've been working on a multi-threaded JavaScript runtime implementation for the past week. I have a proof of concept made in C++ using JavaScriptCore and boost. The architecture is simple: when the ...
0
votes
0answers
73 views

What to use in case of waiting for something that is complete: delegates, events and/or thread

I try to give a concrete example. Create a semaphore for a crossroads. I have two semaphores. I have possibility to set a duration of semaphore 2 minutes, 5 minutes, 10m inutes etc. When one ...
5
votes
2answers
356 views

Why is threading platform-dependent?

I am reading book "Foundations of Qt Development", Chapter 12, and I read that threading is platform-dependent, can someone explain, why? I know how to use threads but that what they said is not so ...
0
votes
0answers
52 views

Design of thread pool reuse with Executors.newFixedThreadPool in Java [migrated]

In my application I have a code, which should run every hour on a new items and execute some expensive operation with multi threading. Code fragment: int i = 1; //noinspection InfiniteLoopStatement ...
-3
votes
1answer
114 views

C# Share Datatable in Multi-threading

I am beginner in Multi-threading in C# & confuse in current task. My task is to read datatable and display datatable in C# console application using multi threading. I have three threads and one ...
-1
votes
2answers
80 views

Which is better either creating two objects for two threads or one object for two threads?

In the below program, I'm calling method1() of SampleClass from two threads. So, basically I have created two objects for each thread and called the method1(). I have also seen the scenario of ...
0
votes
2answers
99 views

Lock threads or not lock threads?

I have an application (full-stack) that is used millions of times concurrently. Some vital application properties are managed on the client side (at the time it seemed to be the simplest approach to ...
1
vote
1answer
58 views

«Heavy» object initialization: within each thread or outside and then pass it to the threads as parameter?

Let say there is an array of strings, I have to process. I'm using a «heavy» third-part object which gets the string and performs its analysis. In order to optimize a performance, I create a number of ...
4
votes
3answers
150 views

Transitioning from C++ multithreading to Java multithreading

In C++, I've been accustomed to using threads in the following way: #include <iostream> #include <thread> #include <mutex> std::mutex m; int i = 0; void ...
2
votes
0answers
46 views

ODBC 3 Multiple Statements vs Multiple Connections

So right now I have a single thread to handle all the requests for the database. Let's say I have 400 requests per second for logins / logouts / other stuff, and 400 requests per second which are only ...
4
votes
3answers
295 views

Queue vs Threads

I'm implementing a data processing software. The software gets form the network thousands of events that must be processed in according to rules. I implemented a multi-thread service, which receives ...
0
votes
0answers
45 views

Merging waitable objects

Lets say you have two (or more) objects from which both allow a thread to wait for an event to occur. Foo.Wait(timeout); Bar.Wait(timeout); The main thread wants to wake up when either of these ...
0
votes
1answer
69 views

Blocking queue for token based synchronization

I'm currently looking for a good solution for the following use-case in C++ (preferably C++11 or C++14): The program is running a server with a TCP connection. Other clients can connect at any time ...
4
votes
4answers
573 views

Generate a random color for every user and keep track of created colors. Every color MUST be different

In my app every user that connects to the server needs to get a random distinct color and I have to keep track of them. About 20 to 30 will be connected in the same time. When a user disconnects, his ...
1
vote
4answers
316 views

What is the ninja performance gap, why is it so large, and how can we overcome it?

According to this abstract: The "Ninja gap" [...] is the performance gap between naively written C/C++ code that is parallelism unaware (often serial) and best-optimized code on modern ...
2
votes
1answer
141 views

How to implement a (truly) global variable in a Rails app

How can I best implement a global counter in a Rails API app? (A central component in a system with several.) Basically I have a transaction id I need to increment and roll over past a maximum value. ...
0
votes
1answer
177 views

How to let multiple threads write on the same file [closed]

I have got a text file called "vholders.txt". I am making multiple threads as you can see here ,those threads work with their own given data and at last they write their own output to the ...
0
votes
0answers
105 views

Java Multi-threading

I was solving this question in Java where the user enters a partitioned array. The computer then determines what all elements from that array can be used as pivots. (Pivots are the same pivots that ...
0
votes
1answer
53 views

ThreadPool.QueueUserWorkItem is this example a valid use case?

I need to send out a batch of reminder emails, never more than 100 emails per batch, using authenticated SMTP. This is happening on a WindowsService (no GUI). The SMTP library we're using raises a ...
2
votes
1answer
110 views

Does it make sense to have a user specified thread limit?

I'm developing a C++14 application and would like to take advantage of the new multithreading features, in particular std::async. I have seen a number of applications which allow the user to specify ...
0
votes
1answer
71 views

Create/destroy multiple threads for animations/light effects

I'm developing a program for the Razer Deathadder and Firefly, I am going to create new light effects for the Firefly. I'm doing this in C# with the Colore library. Now these light effects will be ...
0
votes
0answers
60 views

How to prevent parallel calls to model?

While there is some command running which calls methods on some model, how to prevent concurrent calls for critical places in that model? If multiple requests comes in then they should maintain their ...
3
votes
3answers
153 views

What is “Split Data Model”, mentioned in the book “Java Concurrency In Practice”?

I'm learning Java multithreading programming by the book "Java Concurrency In Practice". In chapter 9.4.2 Split Data Model, I read this: From the perspective of the GUI, the Swing table model ...
1
vote
1answer
40 views

Coordinating threads in a multithreaded server

The goal is to develop something similar with a quiz application: there is a server to which players connect. At some point, a game is started. The game consists in asking the players a few multiple ...
3
votes
6answers
213 views

OpenGL, multithreading, and throwing destructors

How do you make an class that properly warns a developer in the future that they've made a mistake somewhere in their implementation that resulted in an object that gets deconstructed in a state that ...
0
votes
2answers
47 views

Double-check locking around initialisation which performs a web request

I've just refactored some code that managed a global state cache of values that didn't have locking to use double check locking. Other than moving the initialisation to a single source (the cache was ...
6
votes
2answers
208 views

Advice for designing API request rate limiter?

I'm in the planning stages of a web application that makes heavy use of data retrieved from a third party's REST API. This data is cached on the server and requested by clients via AJAX. The REST API ...
6
votes
1answer
102 views

Python: Control subprocess from calling thread

I am working on a database interface to a MongoDB using Python Eve as an API. The database stores several documents containing parameters and values needed for some calculations. I wrote a Python ...
2
votes
2answers
192 views

Java Thread.sleep() considerations

I've been doing some testing in an app that I've been involved with for the past little while, and it appears as though some of the code we've written is causing a race condition. What's happening is ...
1
vote
2answers
120 views

Thread-safe events — locking on privately held references

I was reading about delegates and events on this webpage to get a better understanding of them and how they relate to each other. While reading, I came across this statement: That goes against ...
4
votes
2answers
295 views

What is it called when threads are waiting but not deadlocked

The definition of a deadlock is when two or more threads cannot complete their execution because they are mutually blocked and waiting for something from the other thread(s). Is there a similar term ...
1
vote
4answers
287 views

Why is dealing with multiple threads considered difficult? [duplicate]

You can say this is opinion based, but the problem is that everyone's opinion on this issue is same. Even the lead developers say that creating the threads is easy, dealing with them together is ...
10
votes
2answers
429 views

Why do programmers define programming models to replace C/POSIX for parallelism?

Providers of new computer architectures regularly try to introduce new programming models, e.g. recently CUDA/OpenCL for GPGPUs, and displace C/POSIX as the control interface to platform ...
3
votes
1answer
126 views

Minimizing lock time (multithreaded app)

I have a web application written in C# which uses external dll written in C++. Communication between clients (web browsers) and a web application is done using SignalR. For communication between web ...
1
vote
0answers
58 views

When do you need precision with thread execution timing and how do you do it with Java? [closed]

(Under software architecture/design) I'm not sure how my question could be subjective but the message next to the title suggests that it is. I hope I'm not violating the rules here. Under what ...
1
vote
0answers
30 views

Push instead of pull on a list that might change due to a command in addition to events? [closed]

I need to show a refreshable/searchable list of items and update/add-to it whenever an event is published. How do I make sure no events are lost while refreshing/searching is happening? Some sort of ...
1
vote
0answers
95 views

Running simulations in parallel, managing each separately [closed]

Let me preface this by admitting that I am a novice - this is the first real project I am doing outside of a class. I am running a single-threaded C++ simulation several hundred times (i.e. I have ...
-1
votes
1answer
71 views

Approaches to Concurrency [closed]

I’ve been doing some research on the various approaches to concurrency, and I’ve ended up with the following taxonomy: Manual thread based concurrency with locks Asynchronous dispatch queues and ...
5
votes
1answer
108 views

Pthread scheduling (System and Process)

I've read the operating system concepts 8th edition written by abraham silberschatz. However, I don't understand Pthread Scheduling. Thread-library schedules user-level-threads on LWP(Lightweight ...
4
votes
1answer
107 views

Threads: the difference of concurrency between many-to-one model and one-to-one model

I am studying "Threads" part with a textbook, Operating system concepts written by Abraham Silberschatz, Peter, Greg. First, I'm going to say something in the textbook related to my question, and ...
2
votes
4answers
168 views

Is it a good idea to make method behavior depend on the calling thread?

I want to subclass a 3rd party class, in order to make it thread-safe. I have a good idea of how to implement this, but there is a problem: the superclass has a property, which affects the behaviour ...
1
vote
2answers
126 views

Don't quite understand check and set in concurrency

I don't entirely understand check and set behaviour.. here is an example: public static void main(String[] args) { List<String> list = Collections.synchronizedList(new ...
1
vote
0answers
88 views

Better choice of Queue then a ConcurrentLinkedQueue if I have low number of threads in Java

I have two threads, one that is reading messages from the web and putting them into some sort of a queue. The other is suppose to read it. I looked into a ConcurrentLinkedQueue and it looks good for ...
5
votes
1answer
149 views

How can I best test a multithreaded C producer-consumer program? [closed]

How does one best write tests for a multi-threaded producer-consumer C program? I know GDB can be used to debug threads, but I believe GDB also stops the thread currently being debugged while other ...
1
vote
0answers
94 views

Terminology - Difference between thread and process and how they manage DB connections

I've been working more with concurrency in Ruby recently, and I keep seeing various articles using "threads" and "process" interchangeably. What are the actual definitions of these terms? Is a ...