Utilize the ListDictionary.SyncRoot Property to acquire an object that can be employed for synchronizing access to the ListDictionary. ListDictionary is a distinctive collection within the System.Collections Specialized namespace. This particular type serves as a non-generic dictionary and is constructed utilizing a linked list structure.
Syntax:
It has the following syntax:
public virtual object SyncRoot { get; }
Property Value:
An object that enables coordination of ListDictionary entry manipulation.
- Shared Resource
In this instance, a ListDictionary serves as the common resource where concurrent threads can both access and alter this container simultaneously.
- Ensuring Thread Safety
Thread safety is a principle that guarantees proper handling of shared resources when multiple threads are accessing and modifying them to avoid unpredictable outcomes and data corruption.
- Synchronization Technique
locks serve as a primary approach to guarantee thread safety. The lock statement represents a straightforward method to synchronize access to a code block or critical section in C#. Another method is utilizing a Synchronization Object.
A synchronization mechanism, commonly referred to as a lock, is a shared resource utilized by threads to synchronize access to the critical section. Its purpose is to guarantee that only a single thread can execute the critical section at any given moment.
The segment of code responsible for accessing or changing the shared resource is referred to as the critical section. This area requires safeguarding from simultaneous access.
- Implementing Locks on the Critical Section
Releasing the lock is crucial to allow other threads to access the synchronization object and the shared resource. Once the thread exits the critical section, the lock is automatically released, ensuring proper synchronization in multithreaded applications.
The thread releases the lock once it completes its tasks within the critical section, allowing other threads to acquire it and enter the critical section.
- Concurrency Considerations
While locks guarantee thread safety, they may lead to contention and impact system performance. It is crucial to strike a balance between synchronization and enabling concurrency whenever feasible.
- Different Approaches to Synchronization
Other synchronization methods like Monitor, Mutex, Semaphore, or more advanced choices such as ReaderWriterLockSlim could be explored depending on the particular needs.
- Contemporary Concurrent Collections
Concurrent data structures provided by the .NET framework are valuable in modern C# development. Within the 'Collections.Concurrent' namespace, you can find classes like ConcurrentDictionary.
Example:
Let's consider a scenario to demonstrate how to achieve synchronized access to the ListDictionary in C#.
using System;
using System.Collections. Specialized;
using System.Threading;
public class SynchronizedListDictionary
{
private ListDictionary my_Dictionary = new ListDictionary();
private object lock_Object = new object();
public void Add_To_Dictionary(object key, object value)
{
lock (lock_Object)
{
//Operate the lock to ensure synchronization
my_Dictionary.Add(key, value);
Console.WriteLine($"Added key: {key}, value: {value} to the dictionary.");
}
}
public void Remove_From_Dictionary(object key)
{
lock (lock_Object)
{
//Operate the lock to ensure synchronization
my_Dictionary.Remove(key);
Console.WriteLine($"Removed key: {key} from the dictionary.");
}
}
public object GetFromDictionary(object key)
{
lock (lock_Object)
{
//Operate the lock to ensure synchronization
return my_Dictionary[key];
}
}
// Other methods for manipulating the dictionary in a thread-safe manner
public int DictionaryCount
{
get
{
lock (lock_Object)
{
//Operate the lock to ensure synchronization
return my_Dictionary.Count;
}
}
}
}
class Program
{
static void Main()
{
SynchronizedListDictionary example = new SynchronizedListDictionary();
// Creating multiple threads to manipulate the dictionary concurrently
Thread thread_1 = new Thread(() => example.Add_To_Dictionary(1, "One"));
Thread thread_2 = new Thread(() => example.Remove_From_Dictionary(1));
Thread thread_3 = new Thread(() => Console.WriteLine($"Dictionary Count: {example.DictionaryCount}"));
// Starting the threads
thread_1.Start();
thread_2.Start();
thread_3.Start();
// Waiting for threads to finish
thread_1.Join();
thread_2.Join();
thread_3.Join();
Console.ReadLine();
}
}
Output:
Added key: 1, value: One to the dictionary.
Removed key: 1 from the dictionary.
Dictionary Count: 0
Explanation:
The SynchronizedListDictionary Class
In this instance, the class offers synchronized dictionary manipulation functionalities (AddToDictionary, RemoveFromDictionary, GetFromDictionary, and DictionaryCount) and wraps a ListDictionary (my_Dictionary).
It employs the lock keyword within each method to ensure exclusive access to critical sections by a single thread, and it employs a particular object (lock_Object) for synchronization purposes.
- AddToDictionary Method
Inserts a new key-value pair into the dictionary while ensuring thread safety. It displays a notification confirming the addition and maintains synchronized access to the dictionary by employing the lock statement.
- RemoveFromDictionary Method
Delete a specific item from the dictionary in a manner that is safe for concurrent operations within a thread. Display a notification confirming the deletion action and ensure synchronized access to the dictionary by employing the lock statement.
- RetrieveFromDictionary Function
Accessing a value from the dictionary in a manner that ensures thread safety, this method employs the lock statement to synchronize access to the dictionary.
- DictionaryCount Property
Provides a count of key-value pairs in the dictionary in a thread-safe manner by employing the lock statement to synchronize dictionary access.
- Program Class (Main Method)
Creates an instance of SynchronizedListDictionary with the variable name 'example'.
Creates three separate threads, namely thread1, thread2, and thread_3, to execute different dictionary tasks concurrently. These tasks include adding new items to the dictionary, removing existing items, and retrieving the count of items in the dictionary.
Utilize the 'Join' method to initiate the threads and await their completion.
Takes input from the console to delay program termination.