Failed to get image grab finished status

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C

Hi, Dear Coders,

I had a project: grab an image, then process the image.
Process like this:
1)In thread 1(file1.c): ... -> grab image start -> wait for grab finished flag -> process image -> ...
2)In thread 2 (file2.c): grab image, need call the camera API to grab image; when grab finished, set the grab finished flag on;
3)In file3.c: grab image API

My problem is: failed to get the grab finished flag.

Below is my code snippets:

a) file1.c: image grab & processing

//grab image
DWORD dwRet=0.0;
SetEvent(st3SnapStartEv);
//printf("send out snap start signal 1\n");
dwRet=WaitForSingleObject(st3SnapEndEv,1000.0);
switch(dwRet)
{
    case WAIT_FAILED:
        sprintf(tmp,"%s","Snapping St3 image failed");
        WriteSt3ErrorLog(tmp);
        break;
    case WAIT_TIMEOUT:
        sprintf(tmp,"%s","Snapping St3 image timeout");
        WriteSt3ErrorLog(tmp);
        break;
    case WAIT_OBJECT_0:
        break;
}
//printf("snap image 1 finished\n");

b)file2.c: image grabbing thread

DWORD WINAPI St3SnapImageThread(LPVOID arg)
{
	int retV=0; 
	double starttime,endtime;
	char tmp[128]="";
	char logMsg[128]=""; 
	DWORD dwRet;
	
	//printf("I am in St3SnapImageThread...\n");
	while(1)
	{
		ProcessSystemEvents();
		
		ProcessDrawEvents();
		
		dwRet=WaitForSingleObject(st3SnapStartEv,INFINITE);
		switch(dwRet)
		{
			case WAIT_FAILED:
				EnterCriticalSection(GetLogFileCS());
				sprintf(logMsg,"%s \t %s \n",TimeStr(),"wait for St3 snap start signals failed");
				WriteLogFile(logMsg);
				LeaveCriticalSection(GetLogFileCS());
				break;
			case WAIT_TIMEOUT:
				break;
			case WAIT_OBJECT_0:
				//printf("Snap St3 image in\n");
				EnterCriticalSection(GetLtControllerCS());
				OpenSt3BarLight(gparam.st3cam.barlightVal);
				LeaveCriticalSection(GetLtControllerCS());
	
				Delay(0.1);
		
				GetCurrentDateTime(&starttime);
				
				EnterCriticalSection(GetCameraCS());  
				retV=SnapMyImage(ST3CAM);
				LeaveCriticalSection(GetCameraCS());
		
				while(!IsSnapOK(ST3CAM))
				{
					GetCurrentDateTime(&endtime);
					if((endtime-starttime) > 1.0)
					{
						sprintf(tmp,"%s %lf, return value=%d","St3SnapImageThread:ST3 image snapping time cost=",(endtime-starttime),retV);  
						WriteSt3ErrorLog(tmp);
						break;
					}
					DelayWithEventProcessing(0.005);	
				}
				EnterCriticalSection(GetLtControllerCS());  
				CloseSt3BarLight();
				LeaveCriticalSection(GetLtControllerCS()); 
		
				SetEvent(st3SnapEndEv);
				break;
		}
	
		ProcessSystemEvents();
		
		ProcessDrawEvents();
		
		if (GetExitThreadsStatus())					//this part used when we click the 'Close' button on top-right corner 
		{
			EnterCriticalSection(GetLogFileCS());
			sprintf(logMsg,"%s \t %s \n",TimeStr(),"got exit signal in St3 image snapping thread");
			WriteLogFile(logMsg);
			LeaveCriticalSection(GetLogFileCS());
			break; 
		}
	}
	
	return 0;
}

c)file3.c: using API provided by camera vendor to grab an image

int SnapMyImage(int camId)
{
    if (0 == avtcam[camId])
    {
        if (OpenAVTCamera(camId) < 0)
        {
            return -1;
        }
    }

    mbSnapOK[camId] = 0;

    // Start capture engine on the host
    VmbCaptureStart( avtcam[camId] );

    if(camId==0)
        VmbCaptureFrameQueue( avtcam[camId] , &frames[camId], FrameDoneCallback1A );
    else
        VmbCaptureFrameQueue( avtcam[camId] , &frames[camId], FrameDoneCallback2A );

    // Start acquisition on the camera
    VmbFeatureCommandRun( avtcam[camId] , "AcquisitionStart" );

    return 0;
}

In above code, need call a callback function:

FrameDoneCallback1A

;

FrameDoneCallback2A

, as shown below:

void VMB_CALL FrameDoneCallback1A( const VmbHandle_t hCamera , VmbFrame_t *pFrame )
{
    if (VmbFrameStatusComplete == pFrame ->receiveStatus)
    {
        imaqArrayToImage(SourceImage[0], pFrame->buffer, pFrame->width, pFrame->height);
        imaqResample (DestImage[0], SourceImage[0], mnwndWidth[0], mnwndHeight[0], IMAQ_ZERO_ORDER, IMAQ_NO_RECT);

        DisplayMyImage(mnwnd[0], DestImage[0]);;

        mbSnapOK[0] = 1;
        //printf("Snap 0 OK\n");

        if (avtcam[0])      //handle is available
        {
            VmbFeatureCommandRun( avtcam[0] , "AcquisitionStop" );
            VmbCaptureEnd(avtcam[0]);
        }
    }
    else
    {
        VmbCaptureFrameQueue( hCamera , pFrame , FrameDoneCallback1 );
        //printf("Snap 0 failed, try again\n");
    }
}

As we will check snapping status in file2.c:

while(!IsSnapOK(ST3CAM))

So I provide function

IsSnapOK(int camId)

in file3.c as:

int IsSnapOK(int camNum)
{
    return mbSnapOK[camNum];
}

My problem: In single thread, grab single image will be finished in 0.3s, but in multithread (10 threads in total), I will received this line each time:

St3SnapImageThread:ST3 image snapping time cost=1.0320

which means image grabbing will cost more than 1s.

I checked the image grabbed, it is correct.

If In enlong the timeout from 1.0s to 3.0s, the log file will shown as:

St3SnapImageThread:ST3 image snapping time cost=3.036

which means image grabbing will cost more than 3s.

I wonder: why I failed to get the grabbing status: mnSnapOk[0], mnSnapOk[1]?

A): Can you show me why I failed on this?
B): How can I fix this issue?

May I show my problem clearly.
Thank you very much.