Converting a feature's geometry to geojson by calling toJson() can be extremely slow for complex geometries.
Expected Behavior
Convert a complex geometry to geojson in < 100ms
Current Behavior
A 3700 point polygon takes ~646ms, which totals to nearly 2 seconds for us to convert all the geometries of queryRenderedFeatures() to json.
Possible Solution
I've narrowed the issue to the gson serializer, PositionSerializer. It appears creating and tweaking a BigDecimal for each the latitude and longitude is very expensive.
Instead of using PositionSerializer which uses this,
public JsonElement serialize(Position src, Type typeOfSrc, JsonSerializationContext context) {
JsonArray rawCoordinates = new JsonArray();
BigDecimal lat = new BigDecimal(src.getLatitude());
lat = lat.setScale(7, RoundingMode.HALF_UP).stripTrailingZeros();
BigDecimal lon = new BigDecimal(src.getLongitude());
lon = lon.setScale(7, RoundingMode.HALF_UP).stripTrailingZeros();
rawCoordinates.add(new JsonPrimitive(lon));
rawCoordinates.add(new JsonPrimitive(lat));
// Includes altitude
if (src.hasAltitude()) {
rawCoordinates.add(new JsonPrimitive(src.getAltitude()));
}
return rawCoordinates;
}
I overrode the serialize method to do this:
public JsonElement serialize(Position src, Type typeOfSrc, JsonSerializationContext context) {
JsonArray rawCoordinates = new JsonArray();
rawCoordinates.add(trim(src.getLongitude()));
rawCoordinates.add(trim(src.getLatitude()));
return rawCoordinates;
}
private double trim(double input) {
return Math.round(input * 100000000D) / 100000000D;
}
and saw a 10x improvement. My call to get json from queryRenderedFeatures went from 2 seconds to 200ms.
I'm sure there's a more elegant/precise solution that what I've created. Just wanted to point it out for anyone else who's having issues with large/complex geometries being very slow to convert.
Converting a feature's geometry to geojson by calling toJson() can be extremely slow for complex geometries.
Expected Behavior
Convert a complex geometry to geojson in < 100ms
Current Behavior
A 3700 point polygon takes ~646ms, which totals to nearly 2 seconds for us to convert all the geometries of queryRenderedFeatures() to json.
Possible Solution
I've narrowed the issue to the gson serializer, PositionSerializer. It appears creating and tweaking a BigDecimal for each the latitude and longitude is very expensive.
Instead of using PositionSerializer which uses this,
I overrode the serialize method to do this:
and saw a 10x improvement. My call to get json from queryRenderedFeatures went from 2 seconds to 200ms.
I'm sure there's a more elegant/precise solution that what I've created. Just wanted to point it out for anyone else who's having issues with large/complex geometries being very slow to convert.