This repo contains a custom layer prototype for displaying real-time USGS earthquake GeoJSON as heatmaps. It's intended to demonstrate one approach for improving parsing performance on large GeoJSON.
It's built using the ArcGIS API for JavaScript and contains a custom feature layer.
Open up your developer console and then run each of these samples:
No web workers - all on main thread
For a fully working sample see the index.html file in this repo. The basic pattern looks like this:
// Reference: https://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
var earthquakeLayer = new EarthquakeLayer({
url: "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_month.geojson"
});
earthquakeLayer.init().then(function(layer){
map.addLayer(layer);
});And, you implement in your code like this:
// EarthquakeLayerSW uses a single web worker
require(["esri/map", "libs/EarthquakeLayerSW","esri/config"], function(Map,EarthquakeLayer,esriConfig) {
map = new Map("map", {
basemap: "topo",
center: [-122.45, 37.75], // longitude, latitude
zoom: 3
});
esriConfig.defaults.io.corsEnabledServers.push("earthquake.usgs.gov");
// Reference: http://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
var earthquakeLayer = new EarthquakeLayer({
url: "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_month.geojson"
});
earthquakeLayer.init().then(function(layer){
map.addLayer(layer);
});
});This project's approach to threading is based on a single task that reoccurs at regularly spaced intervals, such as 5 minutes. For the purposes of this repo the word 'thread' and 'worker' are used interchangeably.
The internal approach to multi-threading following this pattern:
- Break up large GeoJSON file into pieces based on number of threads. One chunk per thread.
- Push each chunk to a thread asynchronously
- Do processing on the thread and return individual results
- Concatenate all results and return single Esri JSON Object.