topic Re: GraphicTracker fails with AccessViolationException in ArcObjects SDK Questions

GraphicTracker fails with AccessViolationException

DavidClarke1 — Wed, 27 Feb 2013 12:52:42 GMT

I am developing an application using the GraphicTracker to display moving icons. I am using the Windows.Forms.Timer event to suspend the display updates for two seconds. I have another couple subroutines that creates and removes GraphicTrackerSymbols to the tracker. All this happens on the same thread as the Windows.Forms.Timer does excute on the main gui thread. I have also verified this in debug.

Every so often the program will crash with an AccessViolationException while trying to set the GraphicTracker.SuspendUpdate property to FALSE; it ALWAYS fails on trying to set that property to "FALSE". What I noticed was that if I do not remove any items from the GraphicTracker it does not fail. When I am removing items here and there as needed at some point it will fail. It may be 30 seconds or 2 minutes. I use the exact same test data (geometry/symbols/coordinates) but it still fails at some "random" time. The map no longer updates on the screen and the whole map is unusable. I cannot seem to recover or continue on. Catching the exception makes no difference as the map just will not work anymore.

Here is the timer code. The timer itself is set to run every 2 seconds.

_gt.SuspendUpdate = False System.Threading.Thread.Sleep(300) _gt.SuspendUpdate = True

My thoughts are that there is some timing issue while using the "Remove" method on the GraphicTracker object that conflicts with the "SuspendUpdate" property. I have tried setting the timer to be a longer or shorter interval and also changing the "Sleep" interval but nothing seems to help.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Thu, 28 Feb 2013 00:22:09 GMT

When I read the Java docs on GraphicTracker, it says the suspendupdate property is false by default.

public boolean isSuspendUpdate() throws IOException, AutomationException

Disables automatic refreshing of the display until unsuspended or until the display is explicitly refreshed. Suspending automatic refresh is ideal before bulk updates.

Description
Suspends update (i.e refresh) of the display. This property is false by default. This means the GraphicTracker will automatically refresh the display after each graphic is changed.
Setting this property to true, moving the graphics and then setting this property to false will result in one refresh call and will draw all graphics at once. In an dynamic map, this property is not relevant.

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Thu, 28 Feb 2013 11:44:40 GMT

You are correct. It is FALSE by default. However, the toggling of that property is on a Windows.Forms.Timer so that it executes every 2 seconds. That way the screen is not updating for every item I move on the screen. In production I will be receiving a continuous stream of GPS data; at this point I am simulating that. Because I am receiving a continuous stream of GPS data, I do not want the screen (via GraphicTracker) to update for every item; the CPU usage would be too high. If I delay by 2 seconds and only allow the screen to update every 2 seconds (via timer) then the CPU is manageable and everything is great, until the error.

Keep in mind this code executes a hundred or even a few thousand times before it fails.

There is an option to run this in Dynamic Display mode which would not require the timer and the CPU would be just a few percent but it is totally useless; there are several bugs and "limitations" when using Dynamic Display which do not allow me to do the things I need to do.

Re: GraphicTracker fails with AccessViolationException

JasonPike — Sat, 11 Dec 2021 16:38:39 GMT

I am developing an application using the GraphicTracker to display moving icons. I am using the Windows.Forms.Timer event to suspend the display updates for two seconds. I have another couple subroutines that creates and removes GraphicTrackerSymbols to the tracker. All this happens on the same thread as the Windows.Forms.Timer does excute on the main gui thread. I have also verified this in debug.

Every so often the program will crash with an AccessViolationException while trying to set the GraphicTracker.SuspendUpdate property to FALSE; it ALWAYS fails on trying to set that property to "FALSE". What I noticed was that if I do not remove any items from the GraphicTracker it does not fail. When I am removing items here and there as needed at some point it will fail. It may be 30 seconds or 2 minutes. I use the exact same test data (geometry/symbols/coordinates) but it still fails at some "random" time. The map no longer updates on the screen and the whole map is unusable. I cannot seem to recover or continue on. Catching the exception makes no difference as the map just will not work anymore.

Here is the timer code. The timer itself is set to run every 2 seconds.
_gt.SuspendUpdate = False
System.Threading.Thread.Sleep(300)
_gt.SuspendUpdate = True
My thoughts are that there is some timing issue while using the "Remove" method on the GraphicTracker object that conflicts with the "SuspendUpdate" property. I have tried setting the timer to be a longer or shorter interval and also changing the "Sleep" interval but nothing seems to help.

There are definitely some problems with the GraphicTracker. I would look at this thread:
http://forums.arcgis.com/threads/72516-Memory-Leak-with-Graphic-Tracker

Also, if you want to find out where the access violation is occurring (to provide ESRI with more information if you file a case) you can use WinDbg and/or Application Verifier:
http://forums.arcgis.com/threads/75186-Memory-leak-with-FeatureClass-object?p=266132#post266132

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Thu, 28 Feb 2013 15:51:23 GMT

I actually saw that thread when I did my initial scan of the ESRI forums looking for answers. For a long while I couldn't reproduce it very well until I figured out removing items from the GraphicTracker triggers it (more often than not). It is still variable the number of deletes before it fails. I will take a look at WinDbg.

Most likely I will report this to ESRI since I am unable to fix this. Unless someone has an idea for me to try (I'm out of ideas).

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Sat, 11 Dec 2021 16:38:41 GMT

David,

Are you doing it backwards?

The Java docs I posted said start with true, do stuff, then set it to false.

Your code is the opposite.

_gt.SuspendUpdate = False 
System.Threading.Thread.Sleep(300) 
_gt.SuspendUpdate = True

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Thu, 28 Feb 2013 17:35:07 GMT

What I am doing causes the screen to only update every 2 seconds which gives me good performance.
What you are suggesting will cause the screen to update FOR 2 seconds then briefly pause.

I hope this makes sense.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Thu, 28 Feb 2013 18:00:13 GMT

Sorry for the confusion David,

Perhaps I'm not getting it either.

When I read the docs, suspend update by default is false, which means as graphics are added or moved or removed, the automatic refresh will occur. I'm stating that from the docs.

Suspending the automatic update, by setting it to TRUE, is what you want for bulk updates. Right? Am I misreading that?

You want to suspend the automatic refresh, add some Graphic Tracker geometry, symbols, etc, then unsuspend the automatic refresh of GraphicTracker, which will refresh your display. Then you want to suspend it again while there are more things to add, then unsuspend, etc.

Are you doing a partial refresh of IActiveView?

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Thu, 28 Feb 2013 18:29:27 GMT

You are reading the documentation perfectly, that is exactly how I understand it as well. I first tried that without success in terms of performance.

You are talking about bulk updates which are different than my continuous stream of data coming in to the application. For my application, I will constantly receive one GPS coordinate at a time (very fast though)

In a sense I am doing what you suggest: for 2 seconds my application is suspending the updates to the screen. During that time I could have received 10 (as a guess) GPS coordinates which are processed by the GraphicTracker with the display still suspended. Now the timer kicks off and I set the property to FALSE allowing the GraphicTracker to update the screen with my 10 updates. After that and a 300 ms sleep, I set the property to TRUE to stop updating the screen for another 2 seconds. This repeats giving me the performance I need in terms of CPU usage.

If I was receiving 10 or so transactions (all at once) every few seconds then I think the method you describe would work great for me. But I am getting these transactions fast but one at a time.

One more thing, I originally tried saving up the GPS coordinates I was receiving into a queue and then doing exactly as you suggest to process them in a bulk manner. However, depending on my circumstances I may not always have a continuous stream of data coming in. So then I would be waiting for a queue to fill up when it may take 10 minutes. I suppose I could try to make a hybrid with a queue while also checking elapsed time.

I have to repeat that this code works for 15 seconds or 10 minutes before failing; I use the same data every time.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Thu, 28 Feb 2013 18:53:52 GMT

How often does your GPS device poll?

I can't think of another way to manually test this than to create a tool add-in that lets me suspend the GraphicTracker, then click,click,click as fast as I can in the map, store those locations in a GraphicTracker then use a timer to unsuspend the GraphicTracker after 2 or 3 seconds, which should refresh my display.

Now, depending on my zoom scale and how many other layers I'm displaying and what kind of symbols I'm using to display the graphics, i can't help but think at some point the GraphicTracker refresh could take longer than normal.

Approximately how many graphics have you added to your GraphicTracker object before everything goes bust?

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Thu, 28 Feb 2013 19:07:40 GMT

Here's a thought. Rather than use a timer, what would happen if you added code to test whether the GraphicsTracker count was divisible by 10 with a remainder of 0, then unsuspend the auto-refresh and re-suspend it? Then your display is refreshing for every 10 graphic objects you add, or you can set it to 20 or whatever.

Perhaps the threading is causing a problem.

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Thu, 28 Feb 2013 19:27:56 GMT

The GPS data I get is sent to me. I cannot poll it. I have to process it as it comes in. Depending on the customer's environment, I could have 2-5 records a second or I could have 2-5 records in 10-15 minutes.

While in debug I have seen as few as 10 items displayed on the screen when it fails. Plus the map I am using is scaled down. Even if I turn off every layer, it will fail.

I have been trying to build a very small application that will exhibit the same failure but it is not complete yet. There are a few other things I am doing that may be factors (text masking for labels and using bitmaps for icons). If I can get that going (or rather to fail), then I could post that code.

Here's a thought. Rather than use a timer, what would happen if you added code to test whether the GraphicsTracker count was divisible by 10 with a remainder of 0, then unsuspend the auto-refresh and re-suspend it? Then your display is refreshing for every 10 graphic objects you add, or you can set it to 20 or whatever.

That could work if I was always adding graphics. However, most times I have items that move on the map so I am using the "MoveTo" method of the GraphicTracker. The graphic count property of the GraphicTracker does not represent the number of transactions I am receiving. Although I could have a counter for how many transactions I get. But then I will have to take into account the times I do not get data for minutes.

Perhaps the threading is causing a problem.

The System.Windows.Forms.Timer object executes on the main GUI thread and I even verified this within debug because I thought maybe the MSDN documentation was lying.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Sat, 11 Dec 2021 16:38:44 GMT

David,

I have a working sample that is based on a Java Tool Add-in, but I believe you can tailor it to your data stream of geometries.

I launch ArcMap 10.0 SP5
I add a layer "ESRI_StreetMap_World_2D" from the services.argisonline.com
I click my Add-in Tool and start clicking in the map.

Initially, for the first five seconds, nothing shows up in the map where I've clicked. After five seconds pass, the previous click points show up and as I click, the current points are added to GraphicTracker for the next 5 seconds, then disappear for 5 seconds, and so on.

I started just above the peninsula and went counter clockwise, zig zagged until I came back around.

[ATTACH=CONFIG]22281[/ATTACH]

Granted, I did not keep this process up for very long. I did go throuh about 5 or 6 suspend/unsuspend iterations though without any problems.

import java.awt.event.MouseEvent;
import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

import com.esri.arcgis.addins.desktop.Tool;
import com.esri.arcgis.arcmapui.IMxDocument;
import com.esri.arcgis.carto.IActiveView;
import com.esri.arcgis.display.IDisplayTransformation;
import com.esri.arcgis.display.IScreenDisplay;
import com.esri.arcgis.display.ISymbol;
import com.esri.arcgis.display.RgbColor;
import com.esri.arcgis.display.SimpleMarkerSymbol;
import com.esri.arcgis.display.esriSimpleMarkerStyle;
import com.esri.arcgis.enginecore.GraphicTracker;
import com.esri.arcgis.enginecore.IGraphicTrackerSymbol;
import com.esri.arcgis.framework.IApplication;
import com.esri.arcgis.geometry.IGeoTransformation;
import com.esri.arcgis.geometry.IGeometry;
import com.esri.arcgis.geometry.IPoint;
import com.esri.arcgis.geometry.ISpatialReference;
import com.esri.arcgis.geometry.Point;
import com.esri.arcgis.geometry.SpatialReferenceEnvironment;
import com.esri.arcgis.interop.AutomationException;


public class GTTool extends Tool {


    /**
     * Called when the tool is activated by clicking it.
     * 
     * @exception java.io.IOException if there are interop problems.
     * @exception com.esri.arcgis.interop.AutomationException if the component throws an ArcObjects exception.
     */
    @Override
    public void activate() throws IOException, AutomationException {
        
    }

    @Override
    public void init(IApplication app) throws IOException, AutomationException {
        super.init(app);
        mxDoc = (IMxDocument)app.getDocument();
    }

    @Override
    public void mousePressed(MouseEvent mouseEvent) {
        super.mousePressed(mouseEvent);
        
        try {
            // Create a point based on the user's mouse click.
            Point p1 = new Point();
            p1.putCoords((double)mouseEvent.getX(), (double)mouseEvent.getY());

            if(gt == null){
                // Instantiate a GraphicTracker and initialize it once.
                //  GraphicTracker by default will refresh after each geometry add
                gt = new GraphicTracker();
                gt.initialize(mxDoc.getActiveView().getFocusMap());
                
                // Tell the GraphicTracker that we want to suspend auto refresh.
                gt.setSuspendUpdate(true);
                
                // Create a timer task to toggle the automatic graphic tracker refresh for the duration in milliseconds.
                //  intially for 5 seconds and every 5 seconds after that.
                Timer timer = new Timer();
                timer.scheduleAtFixedRate(new UnSuspendTimerTask(), 5000, 5000);
            }
            
            // Create a color object that is red
            RgbColor color = new RgbColor();
            color.setRed(255);

            // Create a simplemarkersymbol to be used as the symbol for the graphic placed by GraphicTracker
            twoDSymbol = new SimpleMarkerSymbol();
            twoDSymbol.setStyle(esriSimpleMarkerStyle.esriSMSSquare);
            twoDSymbol.setSize(4);
            twoDSymbol.setColor(color);
            
            // Tell the GraphicTracker to create a symbol and assign it to the GraphicTrackerSymbol object
            gts = gt.createSymbol((ISymbol)twoDSymbol, null);
            
            // Conver the user's map click point to something useful..
            Point mapPoint = (Point)getMapCoordinatesFromScreenCoordinates(p1, mxDoc.getActiveView());
            
            // Declare ESRI named constants for projecting data between WGS1984 and NAD83 HARN AZ Central
            int wgs84 = com.esri.arcgis.geometry.esriSRGeoCSType.esriSRGeoCS_WGS1984;
            int geotransformId = com.esri.arcgis.geometry.esriSRGeoTransformationType.esriSRGeoTransformation_NAD1983_To_WGS1984_1;
            int geotransformDirection = com.esri.arcgis.geometry.esriTransformDirection.esriTransformForward;
            
            // Create a SpatialReferenceEnvironment, ISpatialReference and IGeoTransformation
            SpatialReferenceEnvironment spatialRef = new SpatialReferenceEnvironment();
            ISpatialReference gcswgs84 = spatialRef.createGeographicCoordinateSystem(wgs84);
            IGeoTransformation iGeoTransformation = (IGeoTransformation)spatialRef.createGeoTransformation(geotransformId);
            
            // Set the spatial reference of the point to the spatial reference of the map window (activeView)
            mapPoint.setSpatialReferenceByRef(mxDoc.getActiveView().getScreenDisplay().getDisplayTransformation().getSpatialReference());
            
            // Project the point from whatever the activeView spatial reference is to GCS_WGS_1984 World projection - Decimal Degrees
            mapPoint.projectEx(gcswgs84, geotransformDirection, iGeoTransformation, false, 0.0, 0.0);
            
            // Add the geometry and symbol to the GraphicTracker
            gt.add((IGeometry) mapPoint, gts);
            
        } catch (AutomationException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }
    
    public static IPoint getMapCoordinatesFromScreenCoordinates(IPoint screenPoint, IActiveView activeView)throws Exception{

        if (screenPoint == null || screenPoint.isEmpty() || activeView == null)
            return null;

        IScreenDisplay screenDisplay = activeView.getScreenDisplay();
        IDisplayTransformation displayTransformation = screenDisplay.getDisplayTransformation();
        
        // Returns a point in whatever coordinate system the DataFrame is set to
        return displayTransformation.toMapPoint((int)screenPoint.getX(), (int)
            screenPoint.getY());
    }

    public static GraphicTracker gt = null;
    private IGraphicTrackerSymbol gts;
    private SimpleMarkerSymbol twoDSymbol;
    public static IMxDocument mxDoc;
}

class UnSuspendTimerTask extends TimerTask{

    @Override
    public void run() {
        try {
            if(GTTool.gt.isSuspendUpdate()){
                // make it auto refresh
                GTTool.gt.setSuspendUpdate(false);
            } else {
                // don't make it auto refresh
                GTTool.gt.setSuspendUpdate(true);
            }
        } catch (AutomationException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Fri, 01 Mar 2013 10:42:45 GMT

I will take a look and compare with what I am doing.

The failure only seems to happen if I am deleting graphics from the GraphicsTracker. I never have a problem just adding graphics. Since the failure ALWAYS happens while accessing the "SuspendUpdate" property it seems odd to me that it only fails if I have deletes occurring.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Fri, 01 Mar 2013 14:41:00 GMT

If you are deleting graphics, and you get the failure, it would explain your AccessViolationException. Basically, you're reading from memory something that is not there anymore.

Have you revisited your logic when it comes to removing graphics by the id integer? Perhaps the integer id you are trying to remove is not valid?

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Fri, 01 Mar 2013 17:36:27 GMT

I have reviewed my logic for days and longer. While I am willing to accept I've made mistake I cannot see it. I am sure the ID (GLID) is valid before deleting. I'll have to re-explain a little bit because it might not have been clear before.

The error only occurs while accessing the "SuspendUpdate" property not on the "Remove" method. If you try to remove a graphic from the Tracker with an invalid ID as you suggest, it throws a different exception on the "Remove" method.

While my code executes, graphics are added and sometimes removed from the map. At some point while setting the "SuspendUpdate" property, it fails. I cannot pinpoint if this happens directly after removing a graphic. But the code can successfully remove many items before failure.

If I comment the code to remove graphics then it works fine and I haven't seen a failure. While this must be a vital clue it doesn't tell me why the "SuspendUpdate" is blowing up in a separate part of the code. It makes me think the "Remove" method of the GraphicTracker is bugged. Since the error isn't consistent in when it is thrown it is hard to say for sure.

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Mon, 04 Mar 2013 16:22:12 GMT

I was able to code a small project that demonstrates the problem. Run it and open an MXD. Eventually, it will fail.

It was done with Visual Studio 2010.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Tue, 05 Mar 2013 20:22:52 GMT

In MainForm.vb, Sub PrepareMap(), are you sure this is right?

_gpsThread = New System.Threading.Thread(New System.Threading.ParameterizedThreadStart(Sub() CreateGPSData(mapCenter.X, mapCenter.Y)))

When I look at examples, I haven't seen an example that creates a thread like this. The way you did it in Sub CreateGPSData looks like the examples I've seen.

http://msdn.microsoft.com/en-us/library/system.threading.parameterizedthreadstart.aspx?cs-save-lang=1&cs-lang=vb#code-snippet-2

Re: GraphicTracker fails with AccessViolationException

DavidClarke1 — Wed, 06 Mar 2013 10:45:46 GMT

I found that as an alternate way to pass parameters when creating a thread. Someone suggested this as a superior method than passing with the "Start" method on the Thread object. Honestly, I am not sure about that.

For this code example I can pass the parameters either way and the code still fails. I originally did pass on the "Start" method. I have tried MANY things to attempt to resolve this issue.

Re: GraphicTracker fails with AccessViolationException

LeoDonahue — Wed, 06 Mar 2013 12:24:36 GMT

I'm out of suggestions except one.

Can you output (to the console or somewhere) the values of key, coord, coord.GLID before you make the remove call in UpdateGLID? That woud help you sort out what values are trying to be used when it crashes.