Parsing optimization or lazy loading

[zhimbura]

I have a serious performance issue when parsing.

To demonstrate how it works, I wrote the following code to compare the performance of native JSON.parse and Json { ignoreUnknownKeys = true }.decodeFromString

After that, I perform a time measurement via chrome profile and get this result

Json { ignoreUnknownKeys = true }.decodeFromString 1.92s

JSON.parse 23ms

Is it possible to somehow speed up the work? Use partial JSON.parse in js implementation?
For example, create a Kotlin DTO class and populate it like this?

@Serializable
class Foo {
  val bas: String
}

let parseData = JSON.parse ('{"bas": "hello"}')
Object.assing (new Foo (), parseData)

is it possible to somehow speed it up?

[elizarov]

Some ways to get better speed in Kotlin/JS serialization:

1. Don't create Json instance every time. Cache it with val json = JSON { ... my options ... }
2. Use JSON.parse followed by json.decodeFromDynamic (see https://kotlin.github.io/kotlinx.serialization/kotlinx-serialization-json/kotlinx-serialization-json/kotlinx.serialization.json/decode-from-dynamic.html)

(Measure your results, the benefit, if any, depends on your specific data)

[zhimbura]

The option you proposed takes even longer.

And the JSON object is created once.

[elizarov]

But what is the JSON object? Can you provide a self-contained example that we can use to repeat your measurements?

[zhimbura]

More json https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.js/-j-s-o-n/

Unfortunately, I cannot provide you with this particular JSON as it is part of the NDA.

But I can show pieces that could slow down the parsing