枚举值时，"AsyncEnumerableReader"已达到配置的缓冲区最大大小 [英] 'AsyncEnumerableReader' reached the configured maximum size of the buffer when enumerating a value

问题描述

我正在使用返回IAsyncEnumerable<>的async/await方法来从SQL Server数据库中检索行，并通过Web API .Net Core 3.0接口提供它们.它可以正常工作，直到我超过8192行.超出该点的行将失败.我尝试了3个不同的表，每个表的行大小都非常不同.产生8192行后，每次发生故障.这是我看到的错误:

I am using an async/await method returning IAsyncEnumerable<> to retrieve rows from a SQL Server database and provide them via a Web API .Net Core 3.0 interface. It works fine until I exceed 8192 rows. It fails for rows beyond that point. I have tried 3 different tables, each with very different row sizes. Each time the failure occurs after yielding 8192 rows. Here is the error I see:

An unhandled exception occurred while processing the request.
InvalidOperationException: 'AsyncEnumerableReader' reached the configured maximum size of the buffer when enumerating a value of type 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]'. This limit is in place to prevent infinite streams of 'IAsyncEnumerable<>' from continuing indefinitely. If this is not a programming mistake, consider ways to reduce the collection size, or consider manually converting 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]' into a list rather than increasing the limit.
Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadTestDatabase<T>(IAsyncEnumerable<object> value)

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InvalidOperationException: 'AsyncEnumerableReader' reached the configured maximum size of the buffer when enumerating a value of type 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]'. This limit is in place to prevent infinite streams of 'IAsyncEnumerable<>' from continuing indefinitely. If this is not a programming mistake, consider ways to reduce the collection size, or consider manually converting 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]' into a list rather than increasing the limit.
Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadTestDatabase<T>(IAsyncEnumerable<object> value)
Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadTestDatabase<T>(IAsyncEnumerable<object> value)
Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor.ExecuteAsyncEnumerable(ActionContext context, ObjectResult result, IAsyncEnumerable<object> asyncEnumerable)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeResultFilters>g__Awaited|27_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, object state, bool isCompleted)
Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Show raw exception details
System.InvalidOperationException: 'AsyncEnumerableReader' reached the configured maximum size of the buffer when enumerating a value of type 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]'. This limit is in place to prevent infinite streams of 'IAsyncEnumerable<>' from continuing indefinitely. If this is not a programming mistake, consider ways to reduce the collection size, or consider manually converting 'Microsoft.EntityFrameworkCore.TestDatabase.TestDatabaseDbSet`1[TestNamespace.TestClass]' into a list rather than increasing the limit.
   at Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadTestDatabase[T](IAsyncEnumerable`1 value)
   at Microsoft.AspNetCore.Mvc.Infrastructure.AsyncEnumerableReader.ReadTestDatabase[T](IAsyncEnumerable`1 value)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ObjectResultExecutor.ExecuteAsyncEnumerable(ActionContext context, ObjectResult result, IAsyncEnumerable`1 asyncEnumerable)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeResultFilters>g__Awaited|27_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Logged|17_1(ResourceInvoker invoker)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

reached the configured maximum size of the buffer when enumerating a value of type Microsoft.EntityFrameworkCore DbSet  This limit is in place to prevent infinite streams from continuing indefinitely. If this is not a programming mistake, consider ways to reduce the collection size, or consider manually converting Microsoft.EntityFrameworkCore DbSet  into a list rather than increasing the limit.

Microsoft.EntityFrameworkCore.DbSet AsyncEnumerable

推荐答案

发生了什么事

限制来自

获取或设置该ObjectResultExecutor将要缓冲的IAsyncEnumerable的最多条目.

Gets or sets the most number of entries of an IAsyncEnumerable that that ObjectResultExecutor will buffer.

当Value是IAsyncEnumerable的实例时，ObjectResultExecutor将在调用选定的格式化程序之前急切地读取枚举并添加到同步集合中.此属性确定允许执行程序缓冲的最大条目数.

When Value is an instance of IAsyncEnumerable, ObjectResultExecutor will eagerly read the enumeration and add to a synchronous collection prior to invoking the selected formatter. This property determines the most number of entries that the executor is allowed to buffer.

(...)

默认为8192.

修复

我认为从好到坏.

Fix

From best to worst, in my opinion.

我建议不要从Web API返回太多记录.

I'd recommend not to return so many records from a web api.

分页是处理大量记录的一种方法.您可以签出

Paging is one way to deal with large number of records. You could check out Tutorial: Add sorting, filtering, and paging - ASP.NET MVC with EF Core.

MvcOptions.MaxIAsyncEnumerableBufferLimit设置为另一个值.

您可以返回IEnumerable-它将能够处理更多的记录.

You could return IEnumerable - it will be able to handle the higher number of records.

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