A (performance) quirk with JsonSerializer

[giscus[bot]]

A (performance) quirk with JsonSerializer

System.Text.Json.JsonSerializer has a weird quirk in regard to performance and memory management. So we will discuss what is "wrong" with this code: JsonSerializer.Serialize(myObject, new JsonSerializerOptions(...));.

https://steven-giesel.com/blogPost/0e7512b0-c854-4cce-8606-765fcaf1e69c

[kyle69]

I want to say, it's quite logical to re-use an instance of JsonSerializerOptions, isn't it? ^^

[linkdotnet]

Well kind of - sure. If you would just consider the cost of new, then it is pretty neglectable. And that is where the surprise comes in.

And there are many samples where people new up inside the Serialize or Deserialize call: https://grep.app/search?q=%2C%20new%20JsonSerializerOptions&filter[lang][0]=C%23

So one could see this blog post as a reminder to reuse the instance and also as a small deep-dive why it behaves like it does.