![]() ![]() ![]() Since the tenant ID needs to change with each web request, we need to go through some extra steps to make it all work with context pooling. a tenant ID).Ī typical scenario involving context state would be a multi-tenant ASP.NET Core application, where the context instance has a tenant ID which is taken into account by queries (see Global Query Filters for more details). Crucially, the context's OnConfiguring is only invoked once - when the instance context is first created - and so cannot be used to set state which needs to vary (e.g. This means that special care must be taken when the context involves any state that may change between requests. MethodĬontext pooling works by reusing the same context instance across requests this means that it's effectively registered as a Singleton, and the same instance is reused across multiple requests (or DI scopes). The source code is available here, feel free to use it as a basis for your own measurements. Importantly, this benchmarks single-threaded pooling performance, while a real-world contended scenario may have different results benchmark on your platform before making any decisions. As always, results will change with the number of rows, the latency to your database server and other factors. Benchmarksįollowing are the benchmark results for fetching a single row from a SQL Server database running locally on the same machine, with and without context pooling. Once poolSize is exceeded, new context instances are not cached and EF falls back to the non-pooling behavior of creating instances on demand. ![]() The poolSize parameter of the PooledDbContextFactory constructor sets the maximum number of instances retained by the pool (defaults to 1024). Using (var context = factory.CreateDbContext()) To use context pooling without dependency injection, initialize a PooledDbContextFactory and request context instances from it: var options = new factory = new PooledDbContextFactory(options) The poolSize parameter of AddDbContextPool sets the maximum number of instances retained by the pool (defaults to 1024). O => o.UseSqlServer(("WeatherForecastContext"))) To enable context pooling, simply replace AddDbContext with AddDbContextPool: ( Then, instances of that type are obtained through constructor parameters in controllers or Razor Pages. However, if there is an implementation, it will be invoked as a regular method.The typical pattern in an ASP.NET Core app using EF Core involves registering a custom DbContext type into the dependency injection container via AddDbContext. So, if there is no definition other than the declaration for that partial method, the call is just ignored. For a brief, partial methods are defined as extensibility points in a class. If you take a look into the constructors of the DataContext subclass, you will notice that this partial method is called from all the overloaded versions of the constructors in the end.įor those who are new to Partial Methods, please see this MSDN documentation. We are interested in the method called OnCreated() here. Partial void OnCreated() // Other DataContext specific methods #endregion Usually, an auto generated DataContext subclass has a few partial method declarations like the following: Fortunately enough, the Visual Studio 2008 auto generated DataContext subclasses provide an easy way to achieve this target using extensibility through partial methods. We actually want to be able to change the default value of the CommandTimeout property and we want to do it efficiently. But the problem with this approach is, it will introduce code duplication and related issues. One solution to this problem is to set the value of the CommandTimeout before each time a LINQ to SQL DataContext object is created and such a query is invoked. Any database queries taking a longer time to complete than 30 seconds will throw a : Timeout expired Exception. The default value of the DataContext class's CommandTimeout is set to 30 seconds. LINQ to SQL codes that invoke a long running database query/stored procedure end up with a : Timeout expired Exception. The following article will present a way to achieve an application-wide CommandTimeout for your DataContext class. At times, the execution of a LINQ to SQL query may take a longer time and exceed the default value of the DataContext class's CommandTimeout property. ![]()
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