LabWindows/CVI
Running out of memory in temperature logger application
Hello,
I see a strange behavior of a temperature logger application I'm working on, when data buffer size is over (about) 1.5 Milion samples, I get memory (re)allocation error. Samples are integer values. Temperature measurement unit is an Agilent 34970 with a 34901A Mux card and a J type thermocouple.
Application is built around an UI with a Graph Chart and two timers, one for acquiring data and another for display,
samples are generated (in simulation mode, without Agilent 34970, I generate random values) in the sample Timer callback function, while during display Timer callback, they are represented on the Graph Chart using PlotY.
Memory allocation error comes up in simulation mode also. It seems that during operation, application uses a lot of memory - on Processes tab, in Task Manager, I can see up to 700 MBytes, maybe more. This a lot more that I was estimating initialy, that when using integers, data array should not exceed 6 Meg for 1.5 Milion samples. I do not want to be very accurate on estimating the memory requirements for this application, but when a simple application is using 700Meg of system memory, makes me think that something is not quite right ...
Anyway here is the data generation and display code, any suggestions to find the root cause of this issue are welcomed.
/*...*/
static BOOL simulated = TRUE;
static int panelHandle;
static int *Y_Array;
static int Y_Array_Size;
/*...*/
int main (int argc, char *argv[])
{
/* Instrument and UI Initialization*/
Y_Array_Size = 0;
Y_Array = (int *) malloc (sizeof(int));
if (Y_Array == NULL)
return (-1);
DisplayPanel (panelHandle);
RunUserInterface ();
free(Y_Array);
/*... */
}
int CVICALLBACK cbf_SampleTimer (int panel, int control, int event,
void *callbackData, int eventData1, int eventData2)
{
int Meas;
int i,idx,idx_start,lenght,Y_Array_size_start;
ViInt32 DataPoints;
switch (event)
{
case EVENT_TIMER_TICK:
{
if(simulated == FALSE){
/* ... */
} else {
DataPoints = (ViInt32) Random(1480,1520);
for(i=0;i<DataPoints;i++){
/*... Create comma separated measurement string*/
}
}
Y_Array_size_start = Y_Array_Size;
Y_Array_Size += DataPoints;
Y_Array = (int *) realloc (Y_Array, Y_Array_Size * sizeof(int));
if (Y_Array == NULL){
SuspendTimerCallbacks ();
MessagePopup ("Error !!!", "Can't Allocate More Memory for Y_Array!");
QuitUserInterface (0);
break;
}
for (i=0; i< DataPoints; i++){
/* ... read value from the measurement string*/
Y_Array[Y_Array_size_start+i] = Meas; /*Place value in data Array */
}
} break;
}
return 0;
}
int CVICALLBACK cbf_DisplayTimer (int panel, int control, int event,
void *callbackData, int eventData1, int eventData2)
{
int BinarySwVal;
switch (event)
{
case EVENT_TIMER_TICK:
{
GetCtrlVal (panel, PANEL_BINARYSWITCH, &BinarySwVal);
if(BinarySwVal){
DisplayInProgress = 1;
DeleteGraphPlot (panel, PANEL_GRAPH, -1, VAL_IMMEDIATE_DRAW);
PlotY (panel, PANEL_GRAPH, Y_Array, Y_Array_Size, VAL_INTEGER,
VAL_THIN_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, VAL_GREEN); /*Display whole array */
DisplayInProgress = 0;
}
}
break;
}
return 0;
}
