Canvas memory leak

import QtQuick 2.6

ListView {
  width: 320
  height: 480
  model: 1000
  delegate: Canvas {
    id: canvas
    width: parent.width
    height: width

    onPaint: {
      var ctx = getContext("2d")
      ctx.strokeStyle = "red"
      ctx.lineWidth = 2
      ctx.beginPath()
      for (var i = 1; i < 20; ++i) {
        ctx.lineTo(Math.random() * canvas.width, Math.random() * canvas.height);
      }
      ctx.stroke();
    }
  }
}