Questions tagged [concurrency]

In computer science, concurrency is a property of systems in which multiple computations can be performed in overlapping time periods. The computations may be executing on multiple cores in the same chip, preemptively time-shared threads on the same processor, or executed on physically separated processors.

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intersect chanels in go

I have a simple golang app in which I have two background tasks that produce data, Each of them use it's own channel to signel it produced another unit of data. I have a single consumer that needs the ...
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Generic concurrent bounded buffer in C

I just implemented a generic concurrent queue in C, and I'd like some feedback on my implementation, as well as the logic in handling generic data and concurrency. buffer.h ...
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Is this a good way to achieve atomicity? [closed]

I noticed that Knuth's pipelined implementation of MMIX contains a serious bug in the implementation of CSWAP. The issue is that while the implementation ensures ...
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103 views

Fixed-width non-FIFO DispatchQueue

I have implemented a custom concurrent queue on top of GCD which offers two additional pieces of functionality: Limit the maximum number of concurrently executing tasks. Give manual control over ...
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A tiny threads pool in C

I'm a newbie in C, and currently following Stanford CS107 - Programming Paradigms. For assignment 6, I find it'd be better to isolate the threads management from the service logic. The following code ...
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2answers
356 views

Single Producer Single Consumer lockless ring buffer implementation

I am writing a simple ring buffer for my own education. Below is a crack at a strategy described in http://www.cse.cuhk.edu.hk/~pclee/www/pubs/ancs09poster.pdf : Producer and Consumer keep local ...
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Parallelizing identical long-running tasks with Go channels

I have written a program in Go to compute the discrete logarithm mod primes (find \$x\$ such that \$h=g^x\mod p\$), and the algorithm I am using can be easily parallelized. Essentially, I am trying to ...
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2 Weeks into Go: Golang Tour WebCrawler Exercise

I'm on week 2 of learning go. I just completed the golang.org exercise on creating web crawler (https://tour.golang.org/concurrency/10) and I would please like feedback on my code. It feels overly ...
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1answer
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Barging lock in Java

I found myself in need of a lock that allows my server to barge the write lock that might be acquired by my users. It would never interrupt them, but it would jump the line so the next time the write ...
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1answer
117 views

Parallelized web crawler using goroutines and channels

As part of the "a tour of Go" section on golang.org, I was trying to make a (formerly singlethreaded) web crawler parallelized using goroutines. I got it working but it doesn't seem to "...
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112 views

Thread-safe LFU Cache

I am trying to implement a thread-safe LFU cache algorithm, please review my code and would really appreciate some criticism or suggestion. (on naming, design, data structures used, anything) Some ...
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1answer
125 views

Thread-safe LRU Cache Implementation in Java

I am trying to implement a thread-safe LRU cache algorithm, please review my code and would really appreciate some criticism or suggestion. Some assumptions: capacity will be larger than 0 Some ...
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1answer
45 views

SHA256 password cracker - v2 with concurrency

I have updated my previous code with the suggestions. I have also implemented concurrency to speed up the results. I'd be interested for comments on a more efficient use on concurrency / parallel ...
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106 views

SO golang example with infinite for / channel workers

I whipped this up as an example of how infinite loops can often be used to great effect in golang, and also to discuss closing channels and worker communications. It was strictly off the cuff, but I ...
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1answer
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Waiting for goroutines to finish

I have a program that starts a bunch of goroutines, feeds them data and when there is no more data, waits for the goroutines to finish. I use sync.WaitGroup. I am unsure if I am using correctly, in an ...
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1answer
118 views

Speeding up I/O bound python program

I have the following program. I have 90 million domain names split between 87 files. I need to resolve the IP of all. Right now I feel like this is super slow. ...
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1answer
66 views

A Concurrent Tree implementation with consistent snapshot capability

I have a tree in my application from which I need to periodically take a snapshot. I've been using locks so far, but after running into a few deadlock issues I decided to create a lock-free ...
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136 views

Concurrent Web Crawler

Description As an exercise of learning go concurrency patterns, I decided too build a concurrent web crawler. I made use of the argparse module I put up for review a while back. I'm looking for ...
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1answer
56 views

Concurrent dependant routines in a gui application

The idea is that, in my application I have 5 routines named long_process_1, long_process_2, ...
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1answer
52 views

Keep reading user keyboard input if available, while echoing back the latest available

On StackOverflow I have asked a question a few minutes ago, but then by trying a bit more, I found the answer myself, and I'm posting the resulting working code here for review. What the code does, is ...
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Game of Life, thread per cell

In an effort to learn Java's support for concurrency I solved a self-imposed exercise to write a Game of Life simulator in Java, running a separate thread for each cell. Here is my code: ...
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Orchestrating an unknown number of goroutines

I recently wrote a piece of code to parallelise some code with goroutines and I was wondering if I could get some feedback. It looks overly complex... but I'm not sure how I could make it simpler. It'...
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1answer
105 views

A concurrent lock-free Linked Queue implementation

Recently I've been learning about concurrency/parallelism and I decided to implement the Michael&Scott lock-free Linked queue (PDF) as practice. I'm not entirely sure how to test this data ...
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209 views

Dining philosophers problem in Go

I'm new in Golang and haven't done concurrency in a bit. I would love to hear your opinion on my Dining problem Go solution. Description here, with a tl;dr below: Five silent philosophers sit at a ...
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n executions of a periodic goroutine

I'm new to Go and have a use-case for periodically executing an async work-function. I want the interval between work-function executions to be constant (not the time between one finishing and the ...
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Implementing GSL synchronized_value

Core Guidelines mention a type synchronized_value<T>, which supposedly pairs std::mutex with the internal value. I couldn'...
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1answer
46 views

Concurrency mechanism for ensuring repeated threads are executed in a given order

Inspired by the following leet-code Suppose you are given the following code: ...
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258 views

Reading one source Stream by multiple consumers asynchronously

The problem was using single Stream from the HTTP response in multiple consumers simultaneously. For example: while data is loading, I want write it to the some ...
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Why is my Python thread pool faster than my Go worker pool?

I have recently been digging into understanding Golang concurrency, in particular the use of channels and worker pools. I wanted to compare performance between Go and Python (as many have done) ...
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Run non overlapped periodical tasks on user specified executor

I have concurrency tasks in my module: user code is able to instantiate my object and specify Executor service, then user can submit requests to this object which ...
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1answer
204 views

Concurrent Queue with enqueue and dequeue using Stack as underlying data structure

This is a mix of data structure and multi threading concept based question. (This is only for understanding and learning purpose) The language for the solution : Java A Queue with FIFO behavior needs ...
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261 views

C++ latch implementation

Since std::latch is not in many standard C++ libraries, I tried implementing my own, is it OK from memory ordering perspective or ...
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1answer
61 views

Command line dictionary tool, using webscraping

This is my first proper Go program, after completing Go by Example and https://tour.golang.org. I have a background in Python. This program scrapes definitions from Wordnik, then prints them nicely ...
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41 views

infinite generator with eviction

I made a struct that will loop through a list, and return the next element on calls to the Get() method. It also allows to remove elements from the list by calling the Evict() method, and is safe for ...
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1answer
129 views

Banking application - Optimizing java multi-threading code

I created a simple Bank application to make multiple transactions between multiple accounts. It is working as expected. But I want to know can I make the code more optimized. ...
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156 views

One consumer and two producers using threads

I have based this code on Producer-Consumer Threading on Real Python. The idea is that I have 2 producers: One producer will give result every 0.4 to 0.7 seconds, depending on REST call. The second ...
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Executing two database queries concurrently in Go [closed]

I would like to execute two database queries concurrently for quicker response time. Since channels seemed to be too verbose, I came up with the solution below. However, I'm not very confident about ...
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Simple multiple producer and single consumer concurrency pattern

Anyone please review and share your feedback for the following code. Multiple producers generate random integer numbers and a single consumer receives it to display only odd numbers out of it. ...
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1answer
284 views

A multi-thread Producer Consumer, where a Consumer has multiple Producers (C++17) - Part 2

This post is based on A multi-thread Producer Consumer, where a Consumer has multiple Producers (C++17). I am trying to build a Consumer that consumes data from ...
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2k views

A multi-thread Producer Consumer, where a Consumer has multiple Producers (C++17)

EDID: Thank you very much for your feedback. I updated the code and opened a new post for the updated version. See here. This post is loosely based on A multi-threaded Producer Consumer with C++11. ...
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Multi Threaded High Performance txt file parsing

EDIT A port of Björn's answer to C++ with further improvements at bottom achieving up to 2.4GB/s on the reference machine. Text file parsing and processing continues to be a common task. Often it's ...
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Hosted service for queuing and running tasks in parallel in ASP.NET Core

I am attempting to construct a background service for an IIS-hosted ASP.NET Core project that basically queues tasks and runs them, and I decided to go with the ...
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2answers
153 views

Recursive Mergesort using goroutines

When learning a new language, one of my first tasks I like to go through is writing a few different sorting algorithms in that language to help familiarize myself with the syntax and see if there are ...
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1answer
538 views

Thread Safe Bank Transaction: Deposit, Withdrawal, Check Balance and Transfer in Java

I have made a class which is a thread-safe implementation supporting Deposit, Withdrawal, Check Balance Querying and Transferring of money. I have a class Account: ...
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89 views

Code to print even and Odd number using two threads

Below I am giving you my code which I wrote to print even number using even thread and odd number using odd thread sequentially. Could anyone please validate my code whether it is correct way of ...
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1answer
73 views

Concurrency-safe task scheduler

I'm trying to do some task scheduler and worker. Tasks are added to the queue from which worker retrieves and processes them. Tasks from one queue must be executed sequentially. Tasks from different ...
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1answer
3k views

Simple Producer-consumer implementation in Python

I implemented a simple solution to the Producer–consumer problem that I'd love for you to take a look at. The producer simply adds random numbers to a queue and the consumer (from a separate thread) ...
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Concurrent execution and coordination of C# tasks

I have a class, 'TaskCoordinator' which has 'BaseTask's applied to it. The BaseTasks have OnStarted, OnFinished and OnCancelled events which are triggered to notify the calling class of their events....
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43 views

Concurrency control between a non-blocking and a blocking methods

In this program, there is a list of Holders that is managed by a singleton class. Each of the Holders keeps a copy of the ...
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1answer
2k views

Asynchronous parallel ForEach implemented using Task.Run

I wrote a simple implementation of aysnc parallel.ForEach( ... ) All it really does is create a list of tasks and wait for them all to complete and aggregate the ...

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