load远程图片如何释放？

Creator 2.x
#1

cc.log(“showStudyCwImage”,image_url);

    _instance.newUrl = image_url;

    //通过url下载图片方法
    cc.loader.load(image_url,function (err, texture) {
        _instance.newFrame = new cc.SpriteFrame(texture);
        Global.getCurScene().teachingShotCtrl.getComponent("TeacherShotCtrl").show.spriteFrame = _instance.newFrame;
        Global.getCurScene().teachingShotCtrl.getComponent("TeacherShotCtrl").bg.node.active = false;

        if(_instance.oldFrame){
            var deps = cc.loader.getDependsRecursively(_instance.oldFrame);
            cc.loader.release(deps);
            cc.log("释放oldFrame");

            cc.textureCache.removeTextureForKey(_instance.oldUrl);
        }

        _instance.oldFrame = _instance.newFrame;
        _instance.oldUrl = _instance.newUrl;
        cc.log("截图成功！！！！");
    });
    cc.log("showStudyCwImage load finish")
#2

已经用了release，removeTextureForKey，但是内存还是在不断往上涨
这个该怎么办呀