Example writing newline-delimited JSON to a writer (pipe) and reading from it.

main.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
)

func main() {
	type holder struct {
		I int `json:"i"`
	}

	pr, pw := io.Pipe()

	go func() {
		for i := 0; i < 20; i++ {
			if err := json.NewEncoder(pw).Encode(holder{i}); err != nil {
				log.Println("ENCODE ERROR:", err)
				_ = pw.CloseWithError(err)
				return
			}
		}
		pr.CloseWithError(pw.Close())
	}()

	var h holder
	dec := json.NewDecoder(pr)
	for dec.More() {
		if err := dec.Decode(&h); err != nil {
			log.Println("DECODE ERROR:", err)
			_ = pr.CloseWithError(err)
		}
		fmt.Println("decoded", h.I)
	}

	if err := pr.Close(); err != nil {
		log.Println("CLOSE ERROR:", err)
	}
}