HttpClient

HttpClient 类
Bugs and Documentation Errors in .NET's HttpClient Frustrate Developers
C# – Configuring HttpClient connection keep-alive
Should I pass the full URL or just the domain to ServicePointManager.FindServicePoint()?
Use HttpClientFactory from .NET 4.6.2

Class

Setting	Default	.NET Framework	.NET Core
Idle connection timeout	2 mins	ServicePoint.MaxIdleTime	SocketsHttpHandler.PooledIdleConnectionTimeout
Max connection lifetime	Forever	ServicePoint.ConnectionLeaseTimeout	SocketsHttpHandler.PooledConnectionLifetime

In .NET Framework

Set ServicePoint.ConnectionLeaseTimeout to change the max connection lifetime:

//create the single instance
httpClient = new HttpClient();
var sp = ServicePointManager.FindServicePoint(new Uri("https://localhost:9000"));
sp.ConnectionLeaseTimeout = (int)TimeSpan.FromMinutes(5).TotalMilliseconds;

In .NET Core

Set SocketsHttpHandler.PooledConnectionLifetime to change the max connection lifetime:

var socketHttpHandler = new SocketsHttpHandler()
{
	PooledConnectionLifetime = TimeSpan.FromMinutes(5),
};
httpClient = new HttpClient(socketHttpHandler);