I encountered a performance issue when returning a large array of nested objects as response to a GraphQL query and was wondering whether it would be considered an actual performance issue or out of scope. This is a minimal GraphQL API to reproduce the issue, using a generated project with smallrye-graphql and lombok from code.quarkus.io:

@GraphQLApi
public class TestGraphQLAPI {
    private static final List<SomeWrapper> objects = IntStream
            .range(0, 10_000_000)
            .mapToObj(i -> new SomeWrapper("value #" + i))
            .collect(Collectors.toList());

    @Value
    public static class SomeWrapper {
        String someValue;
    }

    @Query
    public List<SomeWrapper> giveMeLargeResponse() {
        return objects;
    }
}

I am querying the endpoint using curl:

curl 'http://localhost:8080/graphql' --data-raw '{"query":"{giveMeLargeResponse {someValue}}","variables":null}' > /dev/null

If I pipe the response to a file, the file is roughly 300MB in size.

The request takes roughly 72s to return on an Intel(R) Core(TM) i9-10900 CPU @ 2.80GHz (1 core fully utilized) and intermittedly takes up around 8.2GB of RAM.

I know 10 million entries is a lot, but I expected the query to return much faster, given that it only needs to serialize and output the data. The majority of the time seems to be spent within completeValueForList:

I attached the VisualVM snapshot data: graphql-performance-10mio.zip