High CPU usage when reading /dev/gpiomem - go

Question

Is there something in my Golang code that would be causing high cpu usage?
The code should read a button on the GPIO pin on a Raspberry Pi 4 (4GB) and when pressed send an REST post message to another program.
I tried using more sleep and no sleep, ive tried changing the code to use a falling edge detection method on the pin. Nothing has changed the high CPU usage.
import (
"fmt"
"github.com/stianeikeland/go-rpio"
"os"
"io/ioutil"
"net/http"
"strings"
"time"
)
func main() {
fmt.Println("Starting Stream Control 0.1")
pinOpenError := rpio.Open()
if pinOpenError != nil {
fmt.Println("Pin Open Error: ", pinOpenError.Error())
os.Exit(1)
}
pin := rpio.Pin(18)
pin.Input()
pin.PullUp()
var PID string
start := time.Now()
StreamRunning := false;
fmt.Println("Reading and Controlling")
for {
res := pin.Read()
if res == 0 {
if StreamRunning == false && time.Since(start).Seconds() > 10{
var StartStreamError error
PID, StartStreamError = StartStream()
if StartStreamError != nil {
fmt.Println("Start Stream Error: ", StartStreamError.Error())
}
fmt.Println("PID = " + PID)
start = time.Now()
StreamRunning = true;
} else {
if time.Since(start).Seconds() > 10 {
StopStream(PID)
StreamRunning = false;
start = time.Now()
}
}
}
time.Sleep(100)
}
}
func postHTTP(url string, requestString string) ([]byte, error){
var blankBody []byte
payload := strings.NewReader(requestString)
client := &http.Client{}
req, clientError := http.NewRequest("POST", url, payload)
if clientError != nil {
return blankBody, clientError
}
req.Header.Add("Content-Type", "application/json")
res, requestError := client.Do(req)
if requestError != nil {
return blankBody, requestError
}
defer res.Body.Close()
returnBody, returnError := ioutil.ReadAll(res.Body)
return returnBody, returnError
}
func StartStream()(string, error) {
fmt.Println("Start Stream")
response, StreamOnError := postHTTP("http://localhost:3000/startStream","{\"devicePath\":\"/dev/video0\",\"streamName\":\"LumiPi-003\"}")
if StreamOnError != nil {
fmt.Println("Stream On Error: ", StreamOnError.Error())
return "0", StreamOnError
}
splitstrings := strings.Split(string(response),",")
for i := range splitstrings {
if strings.Contains(splitstrings[i], "\"pid\":") {
linesplit := strings.Split(splitstrings[i],":")
return linesplit[1], nil
}
}
return "0", nil
}
func StopStream(PID string)(error) {
fmt.Println("Stop Stream")
command := "{\"pid\":" + PID + "}"
_, StreamOnError := postHTTP("http://localhost:3000/stopStream",command)
if StreamOnError != nil {
fmt.Println("Stream Off Error: ", StreamOnError.Error())
return StreamOnError
}
return nil
}
Picture below shows the affect time.sleep has on the program.

Answer 1

The time.Sleep() function was causing the PI to crash when rpio.Open() was still open.
Opening, reading the pins and closing allowed time.Sleep() to be used with a much larger delay which in turn dropped the cpu usage because its not constantly looping.
import (
"fmt"
"github.com/stianeikeland/go-rpio"
"os"
"io/ioutil"
"net/http"
"strings"
"time"
)
func main() {
fmt.Println("Starting Stream Control 0.1")
var PID string
start := time.Now()
StreamRunning := false;
fmt.Println("Reading and Controlling")
for {
pinOpenError := rpio.Open()
if pinOpenError != nil {
fmt.Println("Pin Open Error: ", pinOpenError.Error())
os.Exit(1)
}
pin := rpio.Pin(18)
pin.Input()
pin.PullUp()
res := pin.Read()
rpio.Close()
if res == 0 {
if StreamRunning == false && time.Since(start).Seconds() > 10{
var StartStreamError error
PID, StartStreamError = StartStream()
if StartStreamError != nil {
fmt.Println("Start Stream Error: ", StartStreamError.Error())
}
fmt.Println("PID = " + PID)
start = time.Now()
StreamRunning = true;
} else {
if time.Since(start).Seconds() > 10 {
StopStream(PID)
StreamRunning = false;
start = time.Now()
}
}
}
time.Sleep(100*time.Millisecond)
}
}
func postHTTP(url string, requestString string) ([]byte, error){
var blankBody []byte
payload := strings.NewReader(requestString)
client := &http.Client{}
req, clientError := http.NewRequest("POST", url, payload)
if clientError != nil {
return blankBody, clientError
}
req.Header.Add("Content-Type", "application/json")
res, requestError := client.Do(req)
if requestError != nil {
return blankBody, requestError
}
defer res.Body.Close()
returnBody, returnError := ioutil.ReadAll(res.Body)
return returnBody, returnError
}
func StartStream()(string, error) {
fmt.Println("Start Stream")
response, StreamOnError := postHTTP("http://localhost:3000/startStream","{\"devicePath\":\"/dev/video0\",\"streamName\":\"LumiPi-003\"}")
if StreamOnError != nil {
fmt.Println("Stream On Error: ", StreamOnError.Error())
return "0", StreamOnError
}
splitstrings := strings.Split(string(response),",")
for i := range splitstrings {
if strings.Contains(splitstrings[i], "\"pid\":") {
linesplit := strings.Split(splitstrings[i],":")
return linesplit[1], nil
}
}
return "0", nil
}
func StopStream(PID string)(error) {
fmt.Println("Stop Stream")
command := "{\"pid\":" + PID + "}"
_, StreamOnError := postHTTP("http://localhost:3000/stopStream",command)
if StreamOnError != nil {
fmt.Println("Stream Off Error: ", StreamOnError.Error())
return StreamOnError
}
return nil
}