asp.net core 大并发设置

因为看到https://learn.microsoft.com/en-us/archive/msdn-magazine/2014/october/async-programming-introduction-to-async-await-on-asp-net，文章说异步IO，数据库不消耗线程，故做个测试，结果似乎没看出来异步是否比同步更少消耗线程。可能测试样例不对。但测试出大并发下改如何设置，也算有收获，在此记录。

现在新的.net webapi其实不用asp.net 4的应用程序池，都是“无托管代码”。故，设置IIS并没多大意义。

主要是程序设置：

首先，也是最重要的，ThreadPool.SetMinThreads(work, io);work设置1000，io没有影响设置原先值即可。默认work值是CPU逻辑核数，当请求的并发大时就报502错误，或者线程池开始排队（有Queen值）。

其次，若数据库处理速度很快，则设置.Net数据库连接池MaxSize。我这是SqlServer：Pooling=true;Min pool size=5;Max pool size=1024;Connect Timeout=100。Max pool size影响最大，默认是100。其中，平衡要掌握好。当线程池线程数大于数据库连接池最大数时，将报数据库连接池不足错误（ Connection open error . Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached）。

 

开始测试

代码如下。一个同步，一个异步，两个方法。都执行数据库存储过程，数据库是SqlServer，存储过程等到10秒。 

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Data.SqlClient;
using SqlSugar;
using System.Configuration;
using System.Data;

namespace WebApplication2
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly IConfiguration _configuration;
        public ValuesController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpGet]
        public IActionResult Get()
        {
            return new OkObjectResult(DateTime.Now.ToString());
        }

        [HttpGet("Sync")]
        public IActionResult GetSync()
        {
            string msg = "";
            string? connStr = _configuration.GetValue<string>("DbConfig:ConnectionString");
            using (SqlSugarClient client = new SqlSugarClient(new ConnectionConfig()
            {
                ConnectionString = connStr,
                DbType = SqlSugar.DbType.SqlServer,

            }))
            {
                msg = Thread.CurrentThread.ManagedThreadId.ToString();
                DataSet ds = client.Ado.UseStoredProcedure().GetDataSetAll("TestWait");
                msg += " " + Thread.CurrentThread.ManagedThreadId.ToString();
            }
            return new OkObjectResult(msg + " " + DateTime.Now.ToString());
        }

        [HttpGet("Async")]
        public async Task<IActionResult> GetAsync()
        {
            string msg = "";
            string? connStr = _configuration.GetValue<string>("DbConfig:ConnectionString");
            using (SqlSugarClient client = new SqlSugarClient(new ConnectionConfig()
            {
                ConnectionString = connStr,
                DbType = SqlSugar.DbType.SqlServer,
            }))
            {
                msg = Thread.CurrentThread.ManagedThreadId.ToString();
                DataSet ds = await client.Ado.UseStoredProcedure().GetDataSetAllAsync("TestWait");
                msg += " " + Thread.CurrentThread.ManagedThreadId.ToString();
            }
            return new OkObjectResult(msg + " " + DateTime.Now.ToString());
        }
    }
}

 

 存储过程如下：TestWait

SET QUOTED_IDENTIFIER ON
SET ANSI_NULLS ON
GO
 
CREATE PROC TestWait
AS 
BEGIN

SELECT GETDATE()
WAITFOR DELAY N'00:00:10'
SELECT GETDATE()

END 
GO

  

JMeter压测，dotnet-counters监控（https://learn.microsoft.com/zh-cn/dotnet/core/diagnostics/dotnet-counters）

1、发出测试，1000个1秒内发送。

 

2、监控线程池。 .\dotnet-counters.exe monitor -p 10580 --counters Microsoft.AspNetCore.Hosting,System.Runtime

看到线程池排大队，但线程池由于爬坡算法，不会迅速增加线程，故导致很多http返回502。

 而且实际非常长，将近4分钟。

 

修改程序参数，再测试：

1、Main内设置参数，ThreadPool.SetMinThreads(1000, 10);

2、 同时，连接字符串添加如下：Pooling=true;Min pool size=5;Max pool size=1024;Connect Timeout=100

 

 

3，看结果。存储过程等待10秒，表现非常不错99%都在21秒内返回，web的紧箍咒解掉了，压力都传入后端数据库。