Printing GraphQL documents is slow

[jturkel]

We did some benchmarking of a possible GraphQL gateway built on top of this library and noticed that serializing queries takes hundreds of milliseconds. Here's a benchmark that demonstrate the issue and compares results to wundergraph/graphql-go-tools:

package main

import (
	"os"
	"testing"

	"github.com/graphql-go/graphql/language/parser"
	"github.com/graphql-go/graphql/language/printer"

	"github.com/wundergraph/graphql-go-tools/pkg/astparser"
	"github.com/wundergraph/graphql-go-tools/pkg/astprinter"
)

func BenchmarkPrinter_GraphQLGo(b *testing.B) {
	query, err := os.ReadFile("benchmark_query.graphql")
	if err != nil {
		panic(err)
	}

	document, err := parser.Parse(parser.ParseParams{
		Source: string(query),
	})
	if err != nil {
		panic(err)
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if printer.Print(document) == "" {
			panic("print failed")
		}
	}
}

func BenchmarkPrinter_GraphQLGoTools(b *testing.B) {
	query, err := os.ReadFile("benchmark_query.graphql")
	if err != nil {
		panic(err)
	}

	document, report := astparser.ParseGraphqlDocumentBytes(query)
	if report.HasErrors() {
		panic(report.Error())
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, err := astprinter.PrintString(&document, nil)
		if err != nil {
			panic(err)
		}
	}
}

The benchmark query can be found here and is an anonymized version of a real query in our system. On average graphql-go/graphql takes 303ms to print this query and wundergraph/graphql-go-tools takes 0.018 ms.

[adelsz]

We had just run into the same issue. Printer is terribly slow.