Potential risk of memory leaks

[kimikage]

When using ProfileSVG on Jupyter etc., you can remove <SVG> from the DOM tree by clearing the output cell. But the event handlers may not be collected by the GC. Alternatively, the event handlers may prevent some parts of the <SVG> from being collected by the GC.

This is an essential problem, and it is difficult to solve the problem fundamentally, but I think we can reduce the effects of memory leaks.

The current implementation stores the references to <rect> and <text> nodes in fig,

ProfileSVG.jl/src/svgwriter.jl

Lines 55 to 63 in 8ea09a8

	var fig = {};
	fig.viewport = Snap.select('#$fig_id-viewport');
	fig.frame = Snap.select('#$fig_id-frame');
	fig.viewport_cx = fig.viewport.getBBox().cx;
	fig.rects = Snap.selectAll('#$fig_id-viewport rect');
	fig.texts = Snap.selectAll('#$fig_id-viewport text');

and the event handlers refers them.

ProfileSVG.jl/src/svgwriter.jl

Lines 74 to 98 in 8ea09a8

	fig.rects.forEach(function(rect, i){
	rect.dblclick(function(){
	bbox = rect.getBBox();
	ProfileSVG.move_and_zoom(bbox.cx, bbox.cx, fig.clip_width/bbox.w, fig);
	})
	.mouseover(function(){
	fig.details.nodeValue = rect.node.getAttribute("data-info");
	})
	.mouseout(function(){
	fig.details.nodeValue = "";
	});
	})
	fig.texts.forEach(function(text, i){
	text.dblclick(function(){
	bbox = fig.rects[i].getBBox();
	ProfileSVG.move_and_zoom(bbox.cx, bbox.cx, fig.clip_width/bbox.w, fig);
	})
	.mouseover(function(){
	fig.details.nodeValue = fig.rects[i].node.getAttribute("data-info");
	})
	.mouseout(function(){
	fig.details.nodeValue = "";
	});
	})

The current implementation should work, but there may be memory issues.

Edit:
The issue of holding the references to nodes was slightly improved in PR #26. However, the memory leaks will not be fixed unless we remove all unnecessary references.

[fonsp]

The simplest solution might be:

let svg_node = something // reference to the SVG node
let handler = setInterval(() => {
	if(svg_node.closest("body") == null) {
		// the node got removed from `body`, time to remove our listeners!
		window.removeEventListener("asdf", reference_to_listener_function);
		// etc

		clearInterval(handler)
	}
}, 3000)