I have a closure where I declare and define local variables:
func writer_factory() func() *net.TCPConn {
response_port := "localhost:8000"
tcpAddr_res, err := net.ResolveTCPAddr("tcp4", response_port)
checkError(err)
var response_writer *net.TCPConn
checkError(err)
return func() *net.TCPConn {
if response_writer == nil{
response_writer, err = net.DialTCP("tcp", nil, tcpAddr_res)
checkError(err)
}
return response_writer
}
}
Now my question is, if I call this writer_factory multiple times will I get a memory leak?
So specifically, will I have a memory leak using writer_factory in this program:
package main
import (
"fmt"
"net"
"os"
"strings"
// "io/ioutil"
)
//fmt.Printf("messages are (1) %q
", messages)
func main() {
end_of_message_terminator := "||"
beginning_of_next_message := ""
request := make([]byte, 512)
service_port := ":7777"
tcpAddr, err := net.ResolveTCPAddr("tcp4", service_port)
checkError(err)
listener, err := net.ListenTCP("tcp", tcpAddr)
checkError(err)
for {
response_writer := writer_factory()
conn, err := listener.Accept()
if err != nil {
continue
}
read_len, err := conn.Read(request)
if read_len == 0 {
continue
}
request_string := string(request[:read_len])
messages := strings.Split(request_string, end_of_message_terminator)
messages[0] = beginning_of_next_message + messages[0]
if messages[len(messages) - 1] != "" {
beginning_of_next_message = messages[len(messages) - 1]
messages[len(messages) - 1] = ""
}
if len(messages) == 1 {
continue
}
rw := response_writer()
join_channel := make(chan struct{})
for i := 0; i < len(messages); i++ {
go func(i int, rw *net.TCPConn){
respond_to_message(messages[i], rw)
join_channel <- struct{}{}
}(i, rw)
}
go func (){
for i := 0; i < len(messages); i++ {
<- join_channel
}
rw.Close()
}()
conn.Close()
}
}
func writer_factory() func() *net.TCPConn {
response_port := "localhost:8000"
tcpAddr_res, err := net.ResolveTCPAddr("tcp4", response_port)
checkError(err)
var response_writer *net.TCPConn
checkError(err)
return func() *net.TCPConn {
if response_writer == nil{
response_writer, err = net.DialTCP("tcp", nil, tcpAddr_res)
checkError(err)
}
return response_writer
}
}
func respond_to_message(message string, response_writer *net.TCPConn){
message_parameters := strings.Split(message, "|")
//response_writer.Write([]byte("asti de chris"))
for i := range message_parameters {
param_parts := strings.Split(message_parameters[i], "=")
param_name := param_parts[0]
//param_value := param_parts[1]
response_writer.Write([]byte(param_name))
//fmt.Println(string(result))
}
}
func checkError(err error) {
if err != nil {
fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
os.Exit(1)
}
}
To exercise this code launch the program, then launch this program netcat -l -p 8000 and then this program printf "asti||" | netcat localhost 7777
You can definitely improve performance by using one connection or (if one connection is not thread save) use a sync.Pool. That would save you memory allocations (and with it garbage collection) and also time wasted on opening all those tcp connections.