New to Golang, Yesterday I started to play with Golang and wrote some code which was actually written in PHP, I just wanted to see difference in performance. I am doing the exact same thing in PHP response is exact same in http request but the Golang is performing really slow even after compiling it. I am trying to understand what things that I am using in Golang I shouldn't be using and how can I imporve performance in this piece of Code. I know Iterating over map is slow but PHP using hash maps for implementing multidimentional arrays, well. I can gurantee the sql queries I used were exact same copy pasted from PHP, machines are same, and loop numbers are same in both codes.
package main
import (
"database/sql"
"encoding/json"
"fmt"
_ "github.com/go-sql-driver/mysql"
"net/http"
"reflect"
"strings"
)
func main() {
db, err := sql.Open("mysql", "***:****@tcp(****:3306)/****")
fmt.Println(reflect.TypeOf(db))
checkErr(err)
fmt.Println("Handle Request setup... OK")
http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
jsonData, err := getListings(db)
checkErr(err)
w.Write([]byte(jsonData))
})
fmt.Println("Starting Server....")
fmt.Println("Listening on port 8081")
http.ListenAndServe(":8081", nil)
}
func getListings(db *sql.DB) ([]byte, error) {
var userId string = "142"
normalListings := sqlToArray(db, `******`)
manualListings := sqlToArray(db, "******")
var groupIds []string
for key := range manualListings {
groupId := "142," + manualListings[key]["group_id"]
if !stringInSlice(groupId, groupIds) {
groupIds = append(groupIds, groupId)
}
}
var groupIdsString string
groupIdsString = strings.Join(groupIds, ", ")
manualGroups := sqlToArray(db, "*****")
for key := range manualListings {
for key2 := range manualGroups {
groupId := "142," + manualListings[key]["group_id"]
if groupId == manualGroups[key]["ticket_id"] {
entry := make(map[string]string)
entry["ticket_id"] = manualListings[key]["listing_id"]
entry["date_created"] = manualGroups[key2]["date_created"]
normalListings = append(normalListings, entry)
}
}
}
return json.Marshal(normalListings)
}
func stringInSlice(a string, list []string) bool {
for _, b := range list {
if b == a {
return true
}
}
return false
}
func sqlToArray(db *sql.DB, sqlString string) []map[string]string {
rows, err := db.Query(sqlString)
checkErr(err)
columns, err := rows.Columns()
count := len(columns)
values := make([]interface{}, count)
valuePtrs := make([]interface{}, count)
tableData := make([]map[string]string, 0)
for rows.Next() {
for i := 0; i < count; i++ {
valuePtrs[i] = &values[i]
}
rows.Scan(valuePtrs...)
entry := make(map[string]string)
for i, col := range columns {
val := values[i]
b, ok := val.([]byte)
if ok {
entry[col] = string(b)
} else {
entry[col] = string(b)
}
}
tableData = append(tableData, entry)
}
return tableData
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
Edits: Changed the code to use statically typed structs instead of using maps and Identified the problematic piece of code
New code:
package main
import (
"database/sql"
"encoding/json"
"fmt"
_ "github.com/go-sql-driver/mysql"
"net/http"
"strings"
)
type listingsType struct {
TicketId string
DateCreated string
}
func main() {
db, err := sql.Open("mysql", "******")
checkErr(err)
fmt.Println("Handle Request setup... OK")
http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
jsonData, err := getListings(db)
checkErr(err)
w.Write([]byte(jsonData))
})
fmt.Println("Starting Server....")
fmt.Println("Listening on port 8081")
http.ListenAndServe(":8081", nil)
}
func getListings(db *sql.DB) ([]byte, error) {
var userId string = "142"
normalListings := sqlToArray(db, `*****`)
manualListings := sqlToArray(db, "*****")
var groupIds []string
for _, elem := range manualListings {
groupId := "142," + elem.DateCreated
if !stringInSlice(groupId, groupIds) {
groupIds = append(groupIds, groupId)
}
}
var groupIdsString string
groupIdsString = strings.Join(groupIds, ", ")
fmt.Println(groupIdsString)
manualGroups := sqlToArray(db, "******")
for _, manualList := range manualListings {
for _, manualGroup := range manualGroups {
groupId := "142," + manualList.DateCreated
if groupId == manualGroup.TicketId {
var entry listingsType
entry.TicketId = manualList.TicketId
entry.DateCreated = manualGroup.DateCreated
normalListings = append(normalListings, entry)
}
}
}
return json.Marshal(normalListings)
}
func stringInSlice(a string, list []string) bool {
for _, b := range list {
if b == a {
return true
}
}
return false
}
func sqlToArray(db *sql.DB, sqlString string) []listingsType {
rows, err := db.Query(sqlString)
checkErr(err)
tableData := []listingsType{}
for rows.Next() {
var entry listingsType
rows.Scan(&entry.TicketId, &entry.DateCreated)
tableData = append(tableData, entry)
}
return tableData
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
Problematic piece of code As soon as I comment the following block of code the my code performs just fine. Any idea what is wrong with this loop ?
for _, manualList := range manualListings {
for _, manualGroup := range manualGroups {
groupId := "142," + manualList.DateCreated
if groupId == manualGroup.TicketId {
var entry listingsType
entry.TicketId = manualList.TicketId
entry.DateCreated = manualGroup.DateCreated
normalListings = append(normalListings, entry)
}
}
}
Profiling Result
