我是否在以下代码中获得了异步和等待的好处

Question

我有以下代码，其中我在 GroupBy 子句中使用了 async 关键字，但是智能告诉我这个调用不会等待并将同步运行，我的问题是我对 GetAllLanguages 的两次调用和GetAllStores 和我随后对 Task.WaitAll(languagesTask, storesTask); 的调用使用异步功能，或者我的所有代码都会同步运行，因为我不等待 GroupBy 语句。也可以等待.GroupBy(async resourceApplicationType .. 电话。

 public async Task UpdateAllResources()
        {
            var applicationTypes = databaseSettings.Select(dbcs => dbcs.ResourceApplicationType);
            var commandsPerApplication = applicationTypes
                .GroupBy(async resourceApplicationType =>
                {
                    var languagesTask = GetAllLanguages(resourceApplicationType);
                    var storesTask = GetAllStores(resourceApplicationType);
                    var resourceCategory = ResourceApplicationToCategoriesMapper.Map(resourceApplicationType);
                    Task.WaitAll(languagesTask, storesTask);
                    var commands = from category in resourceCategory
                            from language in languagesTask.Result
                            from store in storesTask.Result
                            select new UpdateResourcesCommand
                            {
                                ApplicationType = resourceApplicationType,
                                StoreCode = store.Code,
                                LocaleCode = language.Locale,
                                ResourceCategory = category
                            };
                    return new
                    {
                        applicationType = resourceApplicationType, commands
                    };
                });

           commandsPerApplication.ForEach(commandsGroup =>
           {
               commandsGroup.Key.Result.commands.ForEach(async command =>
               {
                   await commandExecutor.Execute<UpdateResourcesCommand, Task>(command);
               });
           });
        }

        private Task<IEnumerable<Language>> GetAllLanguages(ResourceApplication applicationType)
        {
            return allLanguagesQueryRetriever.GetByComponentName(InstanceName.GetUniqueName<IAllLanguagesQuery>(applicationType.ToString()))
                .Execute(new AllLanguagesCriteria());
        }

        private Task<IEnumerable<Store>> GetAllStores(ResourceApplication applicationType)
        {
            return allStoresQueryRetriever
                .GetByComponentName(InstanceName.GetUniqueName<IAllStoresQuery>(applicationType.ToString()))
                .Execute(new AllStoresCriteria());
        }

Answer 1

基本的经验法则是“没有等待，异步将同步运行”。

您可以通过将Task.WaitAll() 替换为await Task.WhenAll()，轻松让您的GroupBy() 正常运行async。