Nothing left on event queue.

[MLanghof]

I'm using noLoop() in my sketch and redraw() whenever I have to, which includes mouse interaction. (I use this approach since redraws may be expensive, although this error just happened for a pretty lightweight redraw).

Very occasionally (~once every 10-20 minutes of program usage) I get the following error when I'm performing some action with the mouse that causes a redraw:

java.lang.RuntimeException: Nothing left on the event queue.
	at processing.core.PApplet$InternalEventQueue.remove(PApplet.java:2582)
	at processing.core.PApplet.dequeueEvents(PApplet.java:2614)
	at processing.core.PApplet.postEvent(PApplet.java:2607)
	at processing.opengl.PSurfaceJOGL.nativeMouseEvent(PSurfaceJOGL.java:1139)
	at processing.opengl.PSurfaceJOGL$NEWTMouseListener.mouseDragged(PSurfaceJOGL.java:1034)
	at jogamp.newt.WindowImpl.dispatchMouseEvent(WindowImpl.java:4136)
	at jogamp.newt.WindowImpl.consumePointerEvent(WindowImpl.java:3981)
	at jogamp.newt.WindowImpl.consumeEvent(WindowImpl.java:3376)
	at jogamp.newt.WindowImpl.doEvent(WindowImpl.java:3318)
	at jogamp.newt.WindowImpl.doPointerEvent(WindowImpl.java:3766)
	at jogamp.newt.WindowImpl.doMouseEvent(WindowImpl.java:3426)
	at jogamp.newt.WindowImpl.sendMouseEvent(WindowImpl.java:3393)
	at jogamp.newt.driver.windows.DisplayDriver.DispatchMessages0(Native Method)
	at jogamp.newt.driver.windows.DisplayDriver.dispatchMessagesNative(DisplayDriver.java:124)
	at jogamp.newt.DisplayImpl.dispatchMessages(DisplayImpl.java:753)
	at jogamp.newt.DisplayImpl$7.run(DisplayImpl.java:672)
	at jogamp.newt.DefaultEDTUtil$NEDT.run(DefaultEDTUtil.java:347)

In this case, it happened the moment I started to drag the mouse (while holding LMB). Here are the functions in my applet reacting to mouse input:

void mouseClicked()
{
  processor.handleClick(mouseX, mouseY);
  // Doesn't redraw
}

void mouseWheel(MouseEvent event)
{
  zoom(event.getCount());
  redraw();
}

void mouseDragged()
{
  if (mouseButton == LEFT) {
    panX -= pmouseX - mouseX;
    panY -= pmouseY - mouseY;
  }
  redraw();
}

void mouseReleased()
{
  redraw();
}

Looking at the relevant code, I'm under the impression that multiple events (mouse down and mouse dragged?) get thrown onto the queue and then immediately dequeued from different threads, which InternalEventQueue doesn't guard against. The symptoms definitely yell "race condition", too.

I'd like to note that I'm not doing any threading in my application.

[MLanghof]

Most likely fixed by #4998, closing for now.

[github-actions]

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