multithreading - 为什么使用OmniThreadLibrary Parallel.Pipeline的应用程序在关闭后仍继续在后台运行？

Question

我正在使用OmniThreadLibrary实现用于发送电子邮件的后台pipleline(请参阅此SO question)。我注意到关闭应用程序后，它会继续在后台运行(在Windows Task Manager中可见)。这意味着我实现OTL管道的方式在我的代码中出了点问题。你能帮我找出麻烦吗？

代码如下:

unit uEmailQueue;

interface

uses Classes, OtlCommon, OtlCollections, OtlParallel, Windows;

type
  TEmailServer = record
    SMTPHost: String;
    SMTPPort: Integer;
    SMTPUseSSL: Boolean;
    SMTPUserName: String;
    SMTPPassword: String;
    SMTPSenderName: String;
  end;

  TEmailMessage = record
    RecipientEmailAddr: String;
    EmailSubject: String;
    EmailMessage: String;
  end;

  TEmailQueue = class(TObject)
  private
    FEmailServer: TEmailServer;
    FPipeline: IOmniPipeline;
    procedure SendEmailStage(const input, output: IOmniBlockingCollection);
  public
    constructor Create;
    destructor Destroy; override;
    procedure SendEmail(AEmailMessage: TEmailMessage);
  end;

implementation

{ TEmailQueue }

procedure TEmailQueue.SendEmailStage(const input, output: IOmniBlockingCollection);
var
  mailmessage: TOmniValue;
begin
  for mailmessage in input do
  begin
    Beep(3700, 1500); // just some dummy code for now
  end;
end;

constructor TEmailQueue.Create;
begin
  FPipeline := Parallel.pipeline.Stage(SendEmailStage).Run;

end;

destructor TEmailQueue.Destroy;
begin

  inherited;
end;

procedure TEmailQueue.SendEmail(AEmailMessage: TEmailMessage);
begin
  FPipeline.input.Add(TOmniValue.FromRecord(AEmailMessage));

  // FPipeline.input.CompleteAdding;

  // FPipeline.WaitFor(INFINITE);

end;

end.

我初始化并像上面这样调用上面的类:

在应用程序主窗体的OnCreate事件中:

  FEmailQueue := TEmailQueue.Create;

主窗体上的按钮在OnClick事件中具有以下功能:

var
  em: TEmailMessage;
begin
  FEmailQueue.SendEmail(em);

稍后，我在主窗体的OnDestroy事件中释放了这样的类:

  FEmailQueue.Free;

Answer 1

您应该从FPipeline.input.CompleteAdding调用TEmailQueue.Destroy。否则，SendEmailStage将永远不会停止。