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This article mainly explains "what is the use of object pool Object Pool in .NET Core". The explanation in this article is simple and clear, and is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the use of object pool Object Pool in .NET Core".

What is object Pool

To put it simply, object pool is a kind of software design idea that provides reusability for objects. We often say that it is not difficult to borrow and return, and object pool is to ensure that objects can be reused through two actions such as borrowing and returning, thus saving the performance overhead of frequently creating objects. The most common scenario for object pooling is game design, because there are a large number of reusable objects in the game, and the continuous flow of bullets is not recycled. There is something called connection pooling in the database. Whenever the database cannot be connected, experienced developers often check whether the connection pool is full first, which is actually the specific implementation of the object pooling pattern in a particular domain. So an object pool is essentially a container responsible for the creation and destruction of a set of objects. The biggest advantage of object pooling is the ability to manage each object in the pool independently, deciding whether they need to be recycled or reused. We all know that creating a new object consumes a certain amount of system resources, and once these objects can be reused, it can save system resource overhead, which will be very helpful to improve system performance. The following code is a simple object pool implemented by Microsoft's official documentation:

Public class ObjectPool: IObjectPool {private Func _ instanceFactory; private ConcurrentBag _ instanceItems; public ObjectPool (Func instanceFactory) {_ instanceFactory = instanceFactory? Throw new ArgumentNullException (nameof (instanceFactory)); _ instanceItems = new ConcurrentBag ();} public T Get () {T item; if (_ instanceItems.TryTake (out item)) return item; return _ instanceFactory ();} public void Return (T item) {_ instanceItems.Add (item) Object Pool in .NET Core

Microsoft has provided us with an implementation of object pooling, namely Microsoft.Extensions.ObjectPool, in .NET Core. It mainly provides three core components, namely, ObjectPool, ObjectPoolProvider and IPooledObjectPolicy. ObjectPool is an abstract class that provides Get and Return methods, which is called borrowing and returning. ObjectPoolProvider is also an abstract class, and its job is to create ObjectPool, which provides two Create methods, the difference between which is that the parameterless version essentially uses DefaultPooledObjectPolicy. It, DefaultObjectPool and DefaultObjectPoolProvider are the default implementations provided by Microsoft. IPooledObjectPolicy can define different policies for different object pools to determine how objects can be borrowed and returned. DefaultObjectPool uses ObjectWrapper [] to manage objects internally. The size of ObjectWrapper [] is equal to maximumRetained-1, and by default, maximumRetained is equal to Environment.ProcessorCount * 2. Here, the Interlocked.CompareExchange () method is mainly used.

The specific code is as follows:

Public override T Get () {var item = _ firstItem; if (item = = null | | Interlocked.CompareExchange (ref _ firstItem, null, item)! = item) {var items = _ items; for (var I = 0; I

< items.Length; i++) { item = items[i].Element; if (item != null && Interlocked.CompareExchange(ref items[i].Element, null, item) == item) { return item; } } item = Create(); } return item;}// Non-inline to improve its code quality as uncommon path[MethodImpl(MethodImplOptions.NoInlining)]private T Create() =>

_ fastPolicy?.Create ()? _ policy.Create (); public override void Return (T obj) {if (_ isDefaultPolicy | | (_ fastPolicy?.Return (obj)? _ policy.Return (obj) {if (_ firstItem! = null | | Interlocked.CompareExchange (ref _ firstItem, obj, null)! = null) {var items = _ items; for (var I = 0; I)

< items.Length && Interlocked.CompareExchange(ref items[i].Element, obj, null) != null; ++i) { } } }} 这里用到Interlocked.CompareExchange()方法，Get()方法将items[i].Element和null进行交换，将指定元素设为 null 并返回原始值。Return()方法将items[i].Element和obj交换后的值不为 null，表示指定元素已经归还，这个方法只有在第一个参数和第三个参数相等时才会发生交换。 说了这么多，我们来看一下对象池具体的用法： var service = new ServiceCollection();//使用DefaultObjectPoolProviderservice.AddSingleton();//使用默认策略service.AddSingleton(serviceProvider =>

{var objectPoolProvider = serviceProvider.GetRequiredService (); return objectPoolProvider.Create ();}); / / use custom policy service.AddSingleton (serviceProvider = > {var objectPoolProvider = serviceProvider.GetRequiredService (); return objectPoolProvider.Create (new FooObjectPoolPolicy ());}); var serviceProvider = _ service.BuildServiceProvider (); var objectPool = _ serviceProvider.GetService (); / / borrow and return twice, the same object var item1 = objectPool.Get (); objectPool.Return (item1); var item2 = objectPool.Get (); Assert.AreEqual (item1, item2) / / true// has borrowed but not returned, and the two are different objects var item3 = objectPool.Get (); var item4 = objectPool.Get (); Assert.AreEqual (item3, item4); / / false

In the above code, Foo and FooObjectPoolPolicy are two utility classes:

Public class Foo {public string Id {get; set;} public DateTime? CreatedAt {get; set;} public string CreatedBy {get; set;} public class FooObjectPoolPolicy: IPooledObjectPolicy {public Foo Create () {return new Foo () {Id = Guid.NewGuid () .ToString ("N"), CreatedAt = DateTime.Now, CreatedBy = "zs"};} public bool Return (Foo obj) {return true;}}

TIP: when you need to control how objects in the object pool are created, you can consider implementing a custom IPooledObjectPolicy, whereas the DefaultPooledObjectPolicy implementation is perfect for your use.

Thank you for reading, the above is the content of "what is the use of object pool Object Pool in .NET Core". After the study of this article, I believe you have a deeper understanding of the use of object pool Object Pool in .NET Core, and the specific usage needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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