3

按照文档，我实现了一个库，允许我的 web api 在后台创建和运行任务。基本上，我所做的是创建一个QueuedHostedService（继承自BackgroundService），其中包含要完成的任务并将其添加到队列中。然后通过同时运行这些任务（我想在不同的线程上）逐渐清空这个队列。下面是抽象类BackgroundService

public abstract class BackgroundService : IHostedService, IDisposable
{
    protected BackgroundService();

    public virtual void Dispose();
    //
    // Summary:
    //     Triggered when the application host is ready to start the service.
    //
    // Parameters:
    //   cancellationToken:
    //     Indicates that the start process has been aborted.
    public virtual Task StartAsync(CancellationToken cancellationToken);
    //
    // Summary:
    //     Triggered when the application host is performing a graceful shutdown.
    //
    // Parameters:
    //   cancellationToken:
    //     Indicates that the shutdown process should no longer be graceful.
    [AsyncStateMachine(typeof(<StopAsync>d__4))]
    public virtual Task StopAsync(CancellationToken cancellationToken);
    //
    // Summary:
    //     This method is called when the Microsoft.Extensions.Hosting.IHostedService starts.
    //     The implementation should return a task that represents the lifetime of the long
    //     running operation(s) being performed.
    //
    // Parameters:
    //   stoppingToken:
    //     Triggered when Microsoft.Extensions.Hosting.IHostedService.StopAsync(System.Threading.CancellationToken)
    //     is called.
    //
    // Returns:
    //     A System.Threading.Tasks.Task that represents the long running operations.
    protected abstract Task ExecuteAsync(CancellationToken stoppingToken);

我不知道的是，Task完成后究竟会发生什么？我需要做一些事情（比如使用 Dispose 方法）还是系统负责释放分配给后台线程的资源？

编辑我正在添加实现方法的类QueuedHostedService的实现ExecuteAsinc()

public class QueuedHostedService : BackgroundService
{
    private static ILog logger = LogExtensions.GetClassLogger();

    public QueuedHostedService(IBackgroundTaskQueue taskQueue)
    {
        TaskQueue = taskQueue;
    }

    public IBackgroundTaskQueue TaskQueue { get; }

    protected async override Task ExecuteAsync(CancellationToken cancellationToken)
    {
        logger.MethodEnter();

        while (!cancellationToken.IsCancellationRequested)
        {
            var workItem = await TaskQueue.DequeueAsync(cancellationToken);

            try
            {
                await workItem(cancellationToken);
            }
            catch (Exception ex)
            {
                logger.Error($"Error occurred executing {nameof(workItem)}. with the following exception {ex.Message}");
            }
        }

        logger.MethodLeave();
    }
}
4

0 回答 0