MethodAccessException in WebPlayer

General
1

I get an exception when calling ScanLoop, but only on the webPlayer built using 4.6.3f1 and a* version 3.6.4

It’s a recast graph ca. 4k,1,4k cell:20 tile:20, 4 threads, no penalties, no zip, no gui

    OnScanStatus info = delegate(Progress p) {
        OnCheckForReadyProgress(Mathf.Lerp(0.2f, 0.7f, p.progress), GUIString.LoadingNavigation);
        Console.WriteLine("Scanning:" + p.description + " " + p.progress);
        //Debug.Log("Scanning:" + p.description + " " + p.progress);
    };
    AstarPath.active.ScanLoop(info);

Exception:

MethodAccessException: Attempt to access a private/protected method failed.
  at System.Security.SecurityManager.ThrowException (System.Exception ex) [0x00000] in <filename unknown>:0 
  at Pathfinding.ThreadControlQueue.get_AllReceiversBlocked () [0x00000] in <filename unknown>:0 
  at AstarPath.BlockUntilPathQueueBlocked () [0x00000] in <filename unknown>:0 
  at Pathfinding.AstarData.DeserializeGraphs (System.Byte[] bytes) [0x00000] in <filename unknown>:0 
  at Pathfinding.AstarData.DeserializeGraphs () [0x00000] in <filename unknown>:0 
  at Pathfinding.AstarData.Awake () [0x00000] in <filename unknown>:0 
  at AstarPath.Initialize () [0x00000] in <filename unknown>:0 
  at AstarPath.Awake () [0x00000] in <filename unknown>:0

Leads to this code:

	/** True if blocking and all receivers are waiting for unblocking */
	public bool AllReceiversBlocked {
		get {
			lock (lockObj) {
				return blocked && Thread.VolatileRead (ref blockedReceivers) == numReceivers;
			}
		}
	}
2

Tried so far with no effect.

  • Changing thread count to none has
  • Changing blockedReceivers to internal
  • Changing save/load/caching
  • Tried removing GO and dragging in prefab from new

It seems that I have got some beta code going and reverting the code back to 3.6 fixes everything, looking at the newest beta version now.

return blocked && blockedReceivers == numReceivers;
3

Ah. It seems Thread.VolatileRead is not available in the webplayer. Should have checked that.

4

Now the question is… Why did I add that code. All accesses are done inside locks… It is possible that it is just debugging code and I forgot to remove it…

5

Does it have to do with CPU’s write-buffer flushing their writes?
I found this which seems to be a good read but don’t have the office time to go deep
https://msdn.microsoft.com/en-us/magazine/jj883956.aspx

but I honestly don’t know how much carries to mono

6

I’m getting this too on the webplayer of unity5 with your latest beta version (3.6.7?). You said the code is actually not necessary, do you have a quick workaround? is it safe to comment out the sleep around lines 1892?

7

Hi

As far as I can see, it should be safe to change

return blocked && Thread.VolatileRead (ref blockedReceivers) == numReceivers;

to

return blocked && blockedReceivers == numReceivers;

The reason why the error occurs is because the version of .net that unity uses in the webplayer does not have support for VolatileRead.

1 Like