topic Multiple LayerLists In Web App Cause Slowness in ArcGIS JavaScript Maps SDK Questions

Multiple LayerLists In Web App Cause Slowness

RichardRhone — Fri, 04 Oct 2019 14:22:26 GMT

I have close to 50 layers in my web app. I thought, for easier access and aesthetics, i would employ multiple layerlists. However, this has made the map extremely slow. It takes upwards of 20 seconds to zoom each extent. I presume that since I have 5 layerlist with filtered layers, this essentially equates to 250 layers? How do I improve performance of the map without losing the multiple layerlists?

Re: Multiple LayerLists In Web App Cause Slowness

MattDriscoll — Mon, 07 Oct 2019 22:24:56 GMT

Hi Richard,

What version of the API are you seeing this? I'd like to see if I can trace what is causing the slowness. If you have 50 layers with 5 LayerList widgets you shouldn't be seeing a slowdown like that.

-Matt

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Tue, 08 Oct 2019 12:42:01 GMT

hi Matt,

Im using 4.12

Re: Multiple LayerLists In Web App Cause Slowness

MattDriscoll — Wed, 09 Oct 2019 00:49:14 GMT

Thanks Richard Rhone‌. Can you try using `4.13` which is not yet released but the URL is available. I'm wondering if its still an issue. If it is, i'll create an example using a bunch of layers and multiple LayerLists to test with.

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Wed, 09 Oct 2019 12:42:11 GMT

Hi Matt,

4.13 is actually worse:

4.12 averages out at 18 secs

4.13 averages out at 24 secs

Re: Multiple LayerLists In Web App Cause Slowness

MattDriscoll — Wed, 09 Oct 2019 16:10:51 GMT

Richard Rhone‌ how are you filtering the layers for each LayerList?

- Are you filtering them using layer.listMode?

- Are you using `listItemCreatedFunction` to filter them?

- Some other way?

Re: Multiple LayerLists In Web App Cause Slowness

KristianEkenes — Wed, 09 Oct 2019 16:18:49 GMT

Hi Richard,

I don't think we considered having multiple LayerLists in the same app during the design of the widget. Would using GroupLayers help with the ease of use for maps with lots of layers? You can add layers as sublayers to a GroupLayer, which can be expanded or collapsed for ease of use. The visibilityMode and listMode properties will help in that approach. listMode will control whether a layer's list item is visible in the LayerList or if the children layers of a GroupLayer will be visible. visibilityMode allows you to control how layer visibility can be toggled - either allowing one layer to be visible at a time within the group or if any combination of layers can be toggled on or off.

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Wed, 09 Oct 2019 18:57:46 GMT

Matt...

They are filtered using the example here : https://community.esri.com/thread/239738-multiple-layerlists-in-web-app

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Wed, 09 Oct 2019 19:05:20 GMT

Hi Kristian,

I have used group layers :

/ADD TRANSPORTATION NETWORK GROUP LAYER
var transportationNetworkGroupLayer = new GroupLayer({
title: "Transportation Network", visible: true, visibilityMode: "independent", layers: [otherRoadsLayer, townRoadsLayer, classCRoadsLayer, classBRoadsLayer, classARoadsLayer, highwayLayer, railwayLinesLayer] });
map.add(transportationNetworkGroupLayer);

However, there are still alot of layers to show in one layerList. The thought was to have multiple layerlists for easier access and aesthetics.

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Tue, 12 Nov 2019 20:58:02 GMT

So... I found that the map itself is slow. I have one version with 15 layers and another with 54 layers.

The 15 layer version zooms to extents in less than 1/2 sec. The 50+ layer one zooms in 4 secs. This suggests that its not necessarily the multiple layerlists that are problematic. Is there a limit on the number of layers?

Re: Multiple LayerLists In Web App Cause Slowness

KristianEkenes — Wed, 13 Nov 2019 00:00:27 GMT

There isn't an official limit on the number of layers you can have in your map. It depends on a number of factors, including how much your browser can handle, your hardware (desktop/laptop/mobile device), network latency, how large your layers are, etc.

The larger the layer, the heavier the payload in querying for that data. That also means a lot of smaller layers can add up too.

Can you describe the content of the 54 layers? Are you using them for reference? Editing? Do they represent completely different data for overlay purposes, or do they represent similar features? Based on your snippet above, I figure it's a transportation app. Are they all lines representing road features, or does it include a lot more than that?

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Wed, 13 Nov 2019 12:46:36 GMT

Its an island webmap so it contains roads, civic features, contours, attractions, parcels etc. The heaviest is the parcel layer, but as you rightly point out, the smaller layers add up. There is no editing but we do query some of the layers. Note that the 15 layers one contains the parcels and other necessary layers. I also utilized groupLayers in the 50+ app but there weren't any significant improvements

Re: Multiple LayerLists In Web App Cause Slowness

RichardRhone — Mon, 16 Dec 2019 20:29:50 GMT

So finally i get this thing to work! The layerList with Legend was causing the slowness. Apparently, there is a bug or something that cause the slowness once you exceed a certain number of layers. I added a normal layerList widget and a legend wdget and the slowness was significantly reduced