Http Get example OOM

[damongolding]

The Http Get example on my Seeed Studio XIAO ESP32C3 will eventually hit a out of memory error, roughly around the 8 min mark for me.

I have had some success by calling runtime.GC() at the beginning and end of the loop but I am unsure if this is the best way to combat the underlining issue.

// This example gets an URL using http.Get().  URL scheme can be http or https.
package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"runtime"
	"strings"
	"time"

	"tinygo.org/x/drivers/netdev"
	nl "tinygo.org/x/drivers/netlink"
	link "tinygo.org/x/espradio/netlink"
)

var (
	ssid     string
	password string
)

type ResponseData struct {
	Args    map[string]string `json:"args"`
	Headers map[string]string `json:"headers"`
	Origin  string            `json:"origin"`
	URL     string            `json:"url"`
}

func main() {
	// wait a bit for serial
	time.Sleep(2 * time.Second)

	link := link.Esplink{}
	netdev.UseNetdev(&link)

	println("Connecting to WiFi...")
	err := link.NetConnect(&nl.ConnectParams{
		Ssid:       ssid,
		Passphrase: password,
	})
	if err != nil {
		failure("WiFi connect failed: " + err.Error())
	}

	println("Connected. Getting URL...")
	name := "John Doe"
	occupation := "gardener"

	params := "name=" + url.QueryEscape(name) + "&" +
		"occupation=" + url.QueryEscape(occupation)

	path := fmt.Sprintf("http://httpbin.org/get?%s", params)

	d := &ResponseData{}

	cnt := 0
	for {
		runtime.GC()
		fmt.Printf("Getting %s\r\n\r\n", path)
		resp, err := http.Get(path)
		if err != nil {
			fmt.Printf("problem is %s\r\n", err.Error())
			time.Sleep(10 * time.Second)
			continue
		}

		fmt.Printf("%s %s\r\n", resp.Proto, resp.Status)
		for k, v := range resp.Header {
			fmt.Printf("%s: %s\r\n", k, strings.Join(v, " "))
		}
		fmt.Printf("\r\n")

		body, err := io.ReadAll(resp.Body)
		if err != nil {
			fmt.Printf("%s\r\n", err.Error())
			time.Sleep(10 * time.Second)
			continue
		}

		resp.Body.Close()

		err = json.Unmarshal(body, d)
		if err != nil {
			fmt.Printf("failed to unmarshal: %s\r\n", err.Error())
			time.Sleep(10 * time.Second)
			continue
		}

		fmt.Printf("args: %v\n", d.Args)
		fmt.Printf("headers: %v\n", d.Headers)
		fmt.Printf("origin: %s\n", d.Origin)
		fmt.Printf("url: %s\n", d.URL)

		cnt++
		fmt.Printf("-------- %d --------\r\n", cnt)
		runtime.GC()
		time.Sleep(10 * time.Second)
	}
}

func failure(msg string) {
	for {
		println("failure:", msg)
		time.Sleep(1 * time.Second)
	}
}

[soypat]

Consider using lneto's HTTP library instead of the standard library. The http-app example shows how.

Reason being the Go team was a little careless about heap allocations when designing the standard library http package since Go's GC is really good and modern systems have GBs of memory. Meanwhile, on these small systems you still need libraries that take care not to allocate due to memory constraints due to current limitations of the TinyGo default GC.

[deadprogram]

I think that the arena changes in #42 should help directly address that problem. I might need to increase the default allocation on the esp32c3 however.