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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questions
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Correct synchronization of reads and writes to ConcurrentHashMap and ConcurrentLinkedQueue
I am writing a web application (Servlets, JDBC, no Spring - for learning purposes) that accepts orders from customers, while registered couriers can choose which one of these orders they want to ...
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Rust program to create mail.tm accounts
I have created a rust program to create https://mail.tm accounts, but I think there are things I could have done better. Are there things I can do to improve performance? Are there any unnecessary ...
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Are nested calls to `asyncio.gather()` dangerous?
I wrote this ~100 line script recently, where I tried out Python's asyncio library. When it comes to asynchronous programming in Python, I just have 2 days of ...
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2answers
85 views
Write deduplicated 9-digit numbers from concurrent clients to a log
Problem Statement:
Write a server (“Application”) in Java that opens a socket and restricts input to at most 5 concurrent clients. Clients will connect to the Application and write any number of 9 ...
4
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PyQt load images in background process
I am building an application that needs to load 100-200 images (really only limited by performance) and display them to the user in a sort of gallery. A good analogy would simply be Google Images. In ...
4
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1answer
76 views
Intersect channels 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 signal it produced another unit of data.
I have a single consumer that needs the ...
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2answers
102 views
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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0answers
118 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 ...
4
votes
1answer
83 views
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 ...
4
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2answers
376 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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33 views
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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58 views
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
76 views
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
239 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 "...
2
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1answer
141 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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vote
1answer
201 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 ...
4
votes
1answer
50 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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1answer
206 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
67 views
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 ...
4
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1answer
125 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.
...
4
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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 ...
6
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1answer
149 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 ...
2
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1answer
63 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, ...
2
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1answer
59 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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0answers
32 views
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'...
4
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1answer
141 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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0answers
232 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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0answers
37 views
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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0answers
107 views
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
47 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:
...
8
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1answer
378 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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0answers
52 views
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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0answers
39 views
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
306 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 ...
5
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1answer
332 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
66 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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0answers
42 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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vote
1answer
300 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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4
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1answer
216 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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0answers
28 views
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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2answers
175 views
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
393 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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3answers
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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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2answers
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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 ...
3
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0answers
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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 ...
2
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2answers
190 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
702 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:
...
3
votes
1answer
90 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 ...
