[英]Delphi service fails to stop itself
我运行一个简单的服务。 我可以使用 SCM 启动和停止它。 我还需要该服务在条件成立时自行停止。
问题 1 :当我使用 SCM 时服务停止。 我点击“停止服务”,服务几乎立即停止。 但是我注意到 exe 在停止之前在 Windows 任务列表中停留了大约 10 秒。 这是正常行为吗?
问题 2 :我模拟了一种情况,我需要服务通过增加下面代码示例中的变量来停止自身。 在这种情况下,服务永远不会停止。 我必须在 Windows 任务管理器中终止任务才能停止它。
我尝试了几件事都没有成功。
当我使用SCM停止服务时,ServiceStop调用线程Kill方法,因此线程停止并且服务可以轻轻停止。
当服务想要停止自己时,会从线程本身内部测试条件。 线程会自行停止,但不会停止服务。 所以我想我必须调用 DoShutDown 来告诉服务它必须停止。 但它并没有停止。 无论是否调用 DoShutDown,服务都会继续运行。
我究竟做错了什么 ?
unit TestSvc;
interface
uses
System.SyncObjs
,SysUtils
,Windows
,SvcMgr
,Classes
;
Type
TSvcTh = class(TThread)
private
FEvent : TEvent;
FInterval : Cardinal;
vi_dbg : byte;
protected
procedure Execute; override;
procedure DoTimer;
public
procedure Kill;
Constructor Create();
Destructor Destroy; override;
end;
type
TMyService = class(TService)
procedure ServiceCreate(Sender: TObject);
procedure ServiceStart(Sender: TService; var Started: Boolean);
procedure ServiceShutdown(Sender: TService);
procedure ServiceStop(Sender: TService; var Stopped: Boolean);
private
SelfStop : Boolean;
Svc : TSvcTh;
public
function GetServiceController: TServiceController; override;
end;
var MyService: TMyService;
implementation
procedure ServiceController(CtrlCode: DWord); stdcall;
const sname='ServiceController';
begin
MyService.Controller(CtrlCode);
end;
function TMyService.GetServiceController: TServiceController;
const sname='TMyService.GetServiceController';
begin
Result := ServiceController;
end;
procedure TMyService.ServiceCreate(Sender: TObject);
const sname='TMyService.ServiceCreate';
begin
try
Name := SvcName;
except
on e: exception do begin
end;
end;
end;
procedure TMyService.ServiceShutdown(Sender: TService);
const sname='TMyService.ServiceShutdown';
var Stopped : boolean;
begin
ServiceStop(Self, Stopped);
end;
procedure TMyService.ServiceStart(Sender: TService; var Started: Boolean);
const sname='TMyService.ServiceStart';
begin
SelfStop := false;
Started := false;
try
Dbg(sname + ' ******* STARTING THREAD');
Svc := TSvcTh.Create;
Dbg(sname + '******* THREAD STARTED');
Started := true;
except
on e : exception do begin
Dbg(sname + '============== EXCEPTION =============>' + e.Message);
end;
end;
end;
procedure TMyService.ServiceStop(Sender: TService; var Stopped: Boolean);
const sname='TMyService.ServiceStop';
begin
try
Stopped := True;
if not SelfStop then begin
Dbg(sname + '*** Stop using service controller');
Svc.Kill;
Svc.WaitFor;
Svc.Free;
Svc := nil;
end
else begin
dbg(sname + ' *** Stop by the service itself ') ;
end;
except
on E : Exception do
begin
dbg(sname + ' Exception ! ' + e.Message);
end;
end;
Dbg(sname + '*** END');
end;
procedure TSvcTh.DoTimer;
const sname = 'TSvcTh.DoTimer';
begin
try
inc(vi_dbg);
Dbg(sname + '******* DoTimer');
except
on e : exception do begin
Dbg(sname +' ============== EXCEPTION =============>' + e.Message);
end;
end;
end;
procedure TSvcTh.Execute;
const sname = 'TSvcTh.Execute';
begin
while not Terminated do begin
try
case FEvent.WaitFor(FInterval) of
wrSignaled : begin // Triggered when we stop the service using service controller
Terminate;
end;
wrTimeout : begin
if not Servicemni.SelfStop then begin
DoTimer;
if vi_dbg > 5 then begin
MyService.SelfStop := true; // Testing auto stop
terminate;
end;
end;
end;
end;
except
on e : exception do begin
Dbg(sname + ' ============== EXCEPTION =============>' + e.Message);
end;
end;
end;
if MyService.SelfStop then begin
MyService.DoShutdown;
end;
Dbg(sname + ' ARRET ... ' + StrLog(MyService.Terminated));
if MyService.SelfStop then begin
MyService.ReportStatus;
end;
end;
Constructor TSvcTh.Create();
const sname = 'TSvcTh.Create';
begin
FEvent := TEvent.Create(nil, False, False, '');
FInterval := heartbeat;
vi_dbg := 0;
inherited Create(False);
end;
destructor TSvcTh.Destroy;
const sname = 'TSvcTh.Destroy';
begin
try
if assigned(FEvent) then begin
FreeAndNil(FEvent);
end;
except
on e:exception do begin
Dbg(sname + '==========================> EXCEPTION : '+ e.Message);
end;
end;
inherited;
end;
procedure TSvcTh.Kill;
const sname = 'TSvcTh.Kill';
begin
try
FEvent.SetEvent;
except
on e:exception do begin
dbg(sname + ' ==========================> EXCEPTION : '+ e.Message);
end;
end;
end;
end.
更新 :
如果我添加一个 ServiceExecute 方法并将 Svc 线程修改为仅将 SelfStop 设置为 true(不终止它),则服务结束。 但是看起来不是很优雅。 我不明白为什么需要它。 事实上,该服务似乎无论如何都会创建一个线程“ServiceExecute”。 但是,如果我不编写此方法,则永远不会调用 ProcessRequest,并且当 Svc 线程结束时,“ServiceExecute”永远不会结束。 此外,该进程在服务结束后仍会在 Windows 任务管理器(来自 sysinternals 的进程资源管理器)中停留约 30 秒。
procedure TSvcTh.Execute;
const sname = 'TSvcTh.Execute';
begin
while not Terminated do begin
try
case FEvent.WaitFor(FInterval) of
wrSignaled : begin // Triggered when we stop the service using service controller
Terminate;
end;
wrTimeout : begin
DoTimer;
if vi_dbg > 5 then begin
MyService.SelfStop := true; // Testing auto stop
end;
end;
end;
except
on e : exception do begin
Dbg(sname + ' ============== EXCEPTION =============>' + e.Message);
end;
end;
end;
end;
procedure TMyService.ServiceExecute(Sender: TService);
begin
while not terminated do begin
ServiceThread.ProcessRequests(false);
if SelfStop then begin
ServiceThread.terminate;
Svc.Terminate;
Svc.WaitFor;
Svc.Free;
Svc := nil;
end;
sleep(1000);
end;
更新 2: 服务终止延迟 30 秒的解释似乎在这里
如果线程想要终止自己,它可以调用 SCM 通知服务需要停止,这反过来将终止线程,如下面的概念验证代码所示。 为了完成这项工作,我将一个匿名方法传递给 Thread 构造函数以避免依赖于服务本身(并且可以在服务之外测试线程代码)。 如果您启动该服务并且什么都不做,它将在 10 秒后自行关闭。
服务代码:
unit Unit1;
interface
uses
Unit2,
WinApi.WinSvc,
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.SvcMgr, Vcl.Dialogs;
type
TService1 = class(TService)
procedure ServiceStart(Sender: TService; var Started: Boolean);
procedure ServiceStop(Sender: TService; var Stopped: Boolean);
private
{ Private declarations }
MyThread : TMyThread;
Eventlog : TEventLogger;
public
function GetServiceController: TServiceController; override;
{ Public declarations }
end;
var
Service1: TService1;
implementation
{$R *.dfm}
procedure ServiceController(CtrlCode: DWord); stdcall;
begin
Service1.Controller(CtrlCode);
end;
function TService1.GetServiceController: TServiceController;
begin
Result := ServiceController;
end;
procedure TService1.ServiceStart(Sender: TService; var Started: Boolean);
begin
EventLog := TEventLogger.Create('Service1');
// call our thread and inject code for premature service shutdown
MyThread := TMyThread.Create(procedure begin Service1.Controller(SERVICE_CONTROL_STOP) end);
MyThread.Start;
EventLog.LogMessage('Started');
end;
procedure TService1.ServiceStop(Sender: TService; var Stopped: Boolean);
begin
EventLog.LogMessage('Stop');
MyThread.Terminate;
// Give some time to the thread to cleanup, then bailout
WaitForSingleObject(MyThread.Handle, 5000);
EventLog.LogMessage('Stopped');
EventLog.Free;
Stopped := True;
end;
end.
工作线程:
unit Unit2;
interface
uses
SysUtils,
Vcl.SvcMgr,
Windows,
System.Classes;
type
TSimpleProcedure = reference to procedure;
TMyThread = class(TThread)
private
{ Private declarations }
ShutDownProc : TSimpleProcedure;
EventLog : TEventLogger;
protected
procedure Execute; override;
public
constructor Create(AShutDownProc: TSimpleProcedure);
destructor Destroy; override;
end;
implementation
{ MyThread }
constructor TMyThread.Create(AShutDownProc: TSimpleProcedure);
begin
inherited Create(True);
ShutDownProc := AShutDownProc;
end;
procedure TMyThread.Execute;
var
Count : Integer;
Running : Boolean;
begin
EventLog := TEventLogger.Create('MyThread');
EventLog.LogMessage('Thread Started');
Count := 0;
Running := True;
while not Terminated and Running do
begin
EventLog.LogMessage(Format('Count: %d', [Count]));
Running := Count <> 10;
Inc(Count);
if Running then
Sleep(1000); // do some work
end;
// if thread wants to stop itself, call service thread shutdown and wait for termination
if not Running and not Terminated then
begin
EventLog.LogMessage(Format('Thread Wants to Stop', [Count]));
ShutDownProc();
end;
EventLog.LogMessage(Format('Thread Await terminate', [Count]));
// await termination
while not Terminated do Sleep(10);
EventLog.LogMessage(Format('Thread Terminated', [Count]));
EventLog.Free;
end;
end.
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