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Questions tagged [concurrentdictionary]

ConcurrentDictionary is a .Net thread-safe collection of key-value pairs that can be accessed by multiple threads at the same time.

ConcurrentDictionary is a .Net thread-safe collection of key-value pairs that can be accessed by multiple threads at the same time.

References

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Lock for ConcurrentDictionary when AddOrUpdate-ing?

I use a ConcurrentDictioanry> to access some data across many threads. I read in this article (scroll down) that the method AddOrUpdate is not executed in the lock, so it could endanger thread-safety. My code is as…
Paul
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ConcurrentDictionary - broken dictionary or bad code?

Alright, so I'm running into a strange little issue and frankly I'm out of ideas. I wanted to throw this out there to see if I'm missing something that I've done wrong, or if ConcurrentDictionary isn't working correctly. Here's the code: (Cache is…
Madeline Trotter
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How does this ConcurrentDictionary + Lazy> code work?

There's various posts/answers that say that the .NET/.NET Core's ConcurrentDictionary GetOrAdd method is not thread-safe when the Func delegate is used to calculate the value to insert into the dictionary, if the key didn't already exist. I'm under…
Pure.Krome
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Is it safe to copy a ConcurrentDictionary to a normal Dictionary, by enumerating it directly, based on the current implementation of the class?

TL;DR: Is it possible for a single enumeration of a ConcurrentDictionary, to emit the same key twice? Does the current implementation of the ConcurrentDictionary class (.NET 5) allow this possibility? I have a ConcurrentDictionary…
Theodor Zoulias
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C# Dictionary concurrent add or modify only for different keys, is ConcurrentDictionary necessary?

I have a dictionary only supports add and modify operations and can be concurrently operated, but always for different keys. Keys are int and values are a reference type. Also modify means change some properties of a value. My questions are: Do I…
Student222
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TryRemove a key-value pair from ConcurrentDictionary in C#

The scenario I have is I want a method on ConcurrentDictionary like this. bool TryRemove(TKey key, TValue value) { // remove the value IF the value passed in == dictionary[key] // return false if the key is not in the dictionary, or the…
Frank Bryce
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Using ConcurrentDictionary in a PCL from a UWP app

I recently had a problem and would like some explanation of why : In a Portable Class Library (PCL) using Profile5 (.Net 4, Windows 8) I have this code : using System.Collections.Concurrent; public class Foo { public static void…
Julien Roncaglia
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call valuefactory in concurrent dictionary in async way

I am new to C#'s ConcurrentDictionary class, and I wonder how I can use a valueFactory in the GetOrAdd method in an async way. public class Class1 { public int X = 10; public Class1(int x) { X = x; …
Sean
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Volatile for structs and collections of structs

I would like to use net wisdom to clarify some moments regarding multi-threading in .net. There are a lot of stuff in the internet about it however I was not able to find a good answer to my question. Let say we want to maintain a state of…
irriss
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Different behaviour when collection modified between Dictionary and ConcurrentDictionary

With a normal Dictionary code as list below, I get exception that Collection was modified; enumeration operation may not execute. Dictionary dict2 = new Dictionary(); dict2.Add(1, 10); dict2.Add(2, 20); dict2.Add(3,…
whoami
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Is the list order of a ConcurrentDictionary guaranteed?

I am using a ConcurrentDictionary to store log-lines, and when I need to display them to the user I call ToList() to generate a list. But the weird thing is that some users receive the most recent lines first in the list, while they should logically…
Maestro
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Create a Dictionary using Linq

How can I create a Dictionary (or even better, a ConcurrentDictionary) using Linq? For example, if I have the following XML …
Baruch
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Looping through ConcurrentDictionary while modifying values

I have a static ConcurrentDictionary in a static class. In the static constructor of the class, I call a private method via Task.Run to indefinitely loop through the dictionary and remove items that have expired, i.e. a significant amount of time…
globetrotter
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How to implement tryAdd multiple entries into concurrent dictionary?

I have a concurrent dictionary which I am using it to do some thread-safe functionalities. For example I have the following code : var myConcurrenctDictionary= new ConcurrentDictionary(); if (myConcurrenctDictionary.TryAdd(personId,…
Simple Code
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Is it thread safe to access ConcurrentDictionary values after getting these values with Linq

I have a ConcurrentDictionary like this: ConcurrentDictionary concurrentDictionary = new ConcurrentDictionary(); This is readable and writable dictionary that can be used by many threads. I can manage writable side in a thread…
rodins
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