GenerateKey goes into deadlock state under load #33
Description
I have a simple HTTP server with an endpoint (GET http://localhost:8099/keygen) to generate a key. The handler for this endpoint invokes the GenerateKey func from the emitter-io client.
I have bench-marked this API endpoint, and found that the invocations to GenerateKey results in a deadlock state when I attempt to maintain a set number of concurrent requests for a duration of time. The problem is easily reproducible with 50 concurrent requests over a 2 minute period. Note that the problem is not evident when running a single keygen request at a time.
Here is a sample program to reproduce the deadlock. Ensure to set appropriate values for the SECRET_KEY, BROKER_HOST and BROKER_PORT constants.
Start it with the -race flag: go run -race main.go
package main
import (
"fmt"
"io"
"log"
"net/http"
emitter "github.com/emitter-io/go/v2"
uuid "github.com/satori/go.uuid"
)
const (
SECRET_KEY = "<your_secret_key>"
BROKER_HOST = "172.16.238.16"
BROKER_PORT = "8080"
)
func main() {
// Create the client and connect to the broker
c, err := emitter.Connect(fmt.Sprintf("tcp://%s:%s", BROKER_HOST, BROKER_PORT),
func(_ *emitter.Client, msg emitter.Message) {
log.Fatalf("[emitter] -> [B] received: '%s' topic: '%s'\n", msg.Payload(), msg.Topic())
})
if err != nil {
log.Panic(err)
}
id := c.ID()
fmt.Println("[emitter] -> [B] my name is " + id)
// HTTP server
keygenHandler := func(w http.ResponseWriter, req *http.Request) {
channelId := uuid.NewV4()
var key string
key, err = c.GenerateKey(SECRET_KEY, fmt.Sprintf("channel/%s/", channelId), "r", 600)
if err != nil {
log.Panic(err)
}
fmt.Println(key)
io.WriteString(w, key)
}
http.HandleFunc("/keygen", keygenHandler)
log.Fatal(http.ListenAndServe(":8099", nil))
}
Sample output in console. The data race warning is displayed and the client stopped processing any GenerateKey requests. You have to restart the application for the emitter to process keygen requests again once it got into this state.
[emitter] -> [B] my name is 4V6M6QLQUALAVMBFHYAB4FBUAM
Dth2fColoWPf-ev9oMrALfiR4tHq8IfJ
il0NhYJBE39DjyZEW0E5JE_UkSs1ZpjT
==================
WARNING: DATA RACE
Write at 0x00c000012d10 by goroutine 23:
main.main.func2()
/home/fedora/code/go/src/gallagher.com/emitter/main.go:39 +0x1cc
net/http.HandlerFunc.ServeHTTP()
/usr/local/go/src/net/http/server.go:2012 +0x51
net/http.(*ServeMux).ServeHTTP()
/usr/local/go/src/net/http/server.go:2387 +0x288
net/http.serverHandler.ServeHTTP()
/usr/local/go/src/net/http/server.go:2807 +0xce
net/http.(*conn).serve()
/usr/local/go/src/net/http/server.go:1895 +0x837
Previous write at 0x00c000012d10 by goroutine 17:
main.main.func2()
/home/fedora/code/go/src/gallagher.com/emitter/main.go:39 +0x1cc
net/http.HandlerFunc.ServeHTTP()
/usr/local/go/src/net/http/server.go:2012 +0x51
net/http.(*ServeMux).ServeHTTP()
/usr/local/go/src/net/http/server.go:2387 +0x288
net/http.serverHandler.ServeHTTP()
/usr/local/go/src/net/http/server.go:2807 +0xce
net/http.(*conn).serve()
/usr/local/go/src/net/http/server.go:1895 +0x837
Goroutine 23 (running) created at:
net/http.(*Server).Serve()
/usr/local/go/src/net/http/server.go:2933 +0x5b6
net/http.(*Server).ListenAndServe()
/usr/local/go/src/net/http/server.go:2830 +0x102
net/http.ListenAndServe()
/usr/local/go/src/net/http/server.go:3086 +0x394
main.main()
/home/fedora/code/go/src/gallagher.com/emitter/main.go:50 +0x39f
Goroutine 17 (running) created at:
net/http.(*Server).Serve()
/usr/local/go/src/net/http/server.go:2933 +0x5b6
net/http.(*Server).ListenAndServe()
/usr/local/go/src/net/http/server.go:2830 +0x102
net/http.ListenAndServe()
/usr/local/go/src/net/http/server.go:3086 +0x394
main.main()
/home/fedora/code/go/src/gallagher.com/emitter/main.go:50 +0x39f
==================
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