为什么我在Elixir中使用gen_tcp时一直遇到超时问题？

huangapple
go评论136阅读模式
英文:

Why I keep getting timeout with gen_tcp in Elixir?

问题

我正在尝试实现一个简单的服务器（使用Go语言）/客户端（使用Elixir语言）。

然而，在我的请求到达服务器之前，我一直在Elixir端遇到超时问题。

服务器

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"net"
  6. 	"net/http"
  7. 	"os"
  8. )
  10. func main() {
  11. 	socket := "/tmp/ipc_test.sock"
  12. 	os.Remove(socket)
  14. 	listener, err := net.Listen("unix", socket)
  15. 	if err != nil {
  16. 		fmt.Printf("Error listening on unix socket: %s\n", err)
  17. 		return
  18. 	}
  20. 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
  21. 		param := r.URL.Query().Get("param")
  22. 		fmt.Printf("%s", param)
  23. 		fmt.Fprint(w, param)
  24. 	})
  26. 	fmt.Printf("Server listening on %s\n", socket)
  27. 	http.Serve(listener, nil)
  28. }

客户端

  1. defmodule IpcTest do
  2.   def make_request(socket, request) do
  3.     :gen_tcp.send(socket, request)
  4.     {:ok, response} = :gen_tcp.recv(socket, 0)
  6.     :gen_tcp.close(socket)
  7.     response
  8.   end
  10.   def print_responses(responses) do
  11.     responses
  12.     |> Enum.each(&IO.puts/1)
  13.   end
  15.   def run(num_requests) do
  16.     1..num_requests
  17.     |> Enum.map(fn i ->
  18.       request = "/?param=#{i}"
  20.       Task.async(fn ->
  21.         {:ok, socket} =
  22.           :gen_tcp.connect({:local, "/tmp/ipc_test.sock"}, 0, [:binary, packet: 4, active: false])
  24.         make_request(socket, request)
  25.       end)
  26.     end)
  27.     |> Enum.map(&Task.await/1)
  28.   end
  29. end
  1. > go run src/main.go
  2. Server listening on /tmp/js_runner.sock

如你所见，服务器似乎运行正常。
然而，在我的客户端中，我遇到了以下错误。

  1. > iex -S mix
  2. > IpcTest.run 1
  3. ** (exit) exited in: Task.await(%Task{mfa: {:erlang, :apply, 2}, owner: #PID<0.237.0>, pid: #PID<0.263.0>, ref: #Reference<0.3740412160.2895708166.190144>}, 5000)
  4.     ** (EXIT) time out
  5.     (elixir 1.14.2) lib/task.ex:830: Task.await/2
  6.     (elixir 1.14.2) lib/enum.ex:1658: Enum."-map/2-lists^map/1-0-"/2
  7.     iex:2: (file)
英文:

I am trying to implement a simple Server (in Go) / Client (in Elixir).

However, I keep getting timeouts on Elixir side before my request reaches the server.

Server

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;net&quot;
  6. 	&quot;net/http&quot;
  7. 	&quot;os&quot;
  8. )
  10. func main() {
  11. 	socket := &quot;/tmp/ipc_test.sock&quot;
  12. 	os.Remove(socket)
  14. 	listener, err := net.Listen(&quot;unix&quot;, socket)
  15. 	if err != nil {
  16. 		fmt.Printf(&quot;Error listening on unix socket: %s\n&quot;, err)
  17. 		return
  18. 	}
  20. 	http.HandleFunc(&quot;/&quot;, func(w http.ResponseWriter, r *http.Request) {
  21. 		param := r.URL.Query().Get(&quot;param&quot;)
  22. 		fmt.Printf(&quot;%s&quot;, param)
  23. 		fmt.Fprint(w, param)
  24. 	})
  26. 	fmt.Printf(&quot;Server listening on %s\n&quot;, socket)
  27. 	http.Serve(listener, nil)
  28. }

Client

  1. defmodule IpcTest do
  2.   def make_request(socket, request) do
  3.     :gen_tcp.send(socket, request)
  4.     {:ok, response} = :gen_tcp.recv(socket, 0)
  6.     :gen_tcp.close(socket)
  7.     response
  8.   end
  10.   def print_responses(responses) do
  11.     responses
  12.     |&gt; Enum.each(&amp;IO.puts/1)
  13.   end
  15.   def run(num_requests) do
  16.     1..num_requests
  17.     |&gt; Enum.map(fn i -&gt;
  18.       request = &quot;/?param=#{i}&quot;
  20.       Task.async(fn -&gt;
  21.         {:ok, socket} =
  22.           :gen_tcp.connect({:local, &quot;/tmp/ipc_test.sock&quot;}, 0, [:binary, packet: 4, active: false])
  24.         make_request(socket, request)
  25.       end)
  26.     end)
  27.     |&gt; Enum.map(&amp;Task.await/1)
  28.   end
  29. end
  1. &gt; go run src/main.go
  2. Server listening on /tmp/js_runner.sock

As you can see, the server seems to be running fine.
However, I am getting the following error in my client.

  1. &gt; iex -S mix
  2. &gt; IpcTest.run 1
  3. ** (exit) exited in: Task.await(%Task{mfa: {:erlang, :apply, 2}, owner: #PID&lt;0.237.0&gt;, pid: #PID&lt;0.263.0&gt;, ref: #Reference&lt;0.3740412160.2895708166.190144&gt;}, 5000)
  4.     ** (EXIT) time out
  5.     (elixir 1.14.2) lib/task.ex:830: Task.await/2
  6.     (elixir 1.14.2) lib/enum.ex:1658: Enum.&quot;-map/2-lists^map/1-0-&quot;/2
  7.     iex:2: (file)

答案1

得分: 0

默认情况下，:gen_tcp.connect/3函数的超时值为5000毫秒（5秒）。将其增加到10秒：

  1. {:ok, socket} = :gen_tcp.connect({:local, "/tmp/ipc_test.sock"}, 10000, [])

但你也可以尝试以下命令：

  1. socat - UNIX-CONNECT:/tmp/ipc_test.sock

或者参考这个链接中的其他方法：https://unix.stackexchange.com/questions/26715/how-can-i-communicate-with-a-unix-domain-socket-via-the-shell-on-debian-squeeze

以查看该套接字文件是否对任何正常的Linux命令行工具有效。

英文:

By default, the :gen_tcp.connect/3 function has a timeout value of 5000 milliseconds (5 seconds). Increase to 10:

  1. {:ok, socket} = :gen_tcp.connect({:local, &quot;/tmp/ipc_test.sock&quot;}, 10000, [:

But you should also try stuff like

  1. socat - UNIX-CONNECT:/tmp/ipc_test.sock

Or the other stuff in: https://unix.stackexchange.com/questions/26715/how-can-i-communicate-with-a-unix-domain-socket-via-the-shell-on-debian-squeeze

to see if the socket file is even working for ANY normal linux cli tool.

答案2

得分: 0

搞定了！我的问题实际上出在基于Go的服务器中。

以下是更新后的代码，如果有人感兴趣的话：

  1. package main
  3. import (
  4. 	"io"
  5. 	"log"
  6. 	"net"
  7. 	"os"
  8. )
  10. const SockAddr = "/tmp/ipc_test.sock"
  12. func echoServer(c net.Conn) {
  13. 	log.Printf("客户端已连接 [%s]", c.RemoteAddr().Network())
  14. 	io.Copy(c, c)
  15. 	c.Close()
  16. }
  18. func main() {
  19. 	if err := os.RemoveAll(SockAddr); err != nil {
  20. 		log.Fatal(err)
  21. 	}
  23. 	l, err := net.Listen("unix", SockAddr)
  24. 	if err != nil {
  25. 		log.Fatal("监听错误:", err)
  26. 	}
  27. 	defer l.Close()
  29. 	for {
  30. 		conn, err := l.Accept()
  31. 		if err != nil {
  32. 			log.Fatal("接受错误:", err)
  33. 		}
  35. 		go echoServer(conn)
  36. 	}
  37. }

参考链接：https://eli.thegreenplace.net/2019/unix-domain-sockets-in-go

英文:

Figured it out! My issue was actually in the Go based server.

Here is the updated code if anyone is interested in:

  1. package main
  3. import (
  4. 	&quot;io&quot;
  5. 	&quot;log&quot;
  6. 	&quot;net&quot;
  7. 	&quot;os&quot;
  8. )
  10. const SockAddr = &quot;/tmp/ipc_test.sock&quot;
  12. func echoServer(c net.Conn) {
  13. 	log.Printf(&quot;Client connected [%s]&quot;, c.RemoteAddr().Network())
  14. 	io.Copy(c, c)
  15. 	c.Close()
  16. }
  18. func main() {
  19. 	if err := os.RemoveAll(SockAddr); err != nil {
  20. 		log.Fatal(err)
  21. 	}
  23. 	l, err := net.Listen(&quot;unix&quot;, SockAddr)
  24. 	if err != nil {
  25. 		log.Fatal(&quot;listen error:&quot;, err)
  26. 	}
  27. 	defer l.Close()
  29. 	for {
  30. 		conn, err := l.Accept()
  31. 		if err != nil {
  32. 			log.Fatal(&quot;accept error:&quot;, err)
  33. 		}
  35. 		go echoServer(conn)
  36. 	}
  37. }

Reference: https://eli.thegreenplace.net/2019/unix-domain-sockets-in-go

huangapple
  • 本文由 发表于 2023年7月13日 23:25:03
  • 转载请务必保留本文链接：https://go.coder-hub.com/76681056.html
  • elixir
  • gen-tcp
  • go
  • ipc
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