Scaling FastAGI Applications with Go

Scaling FastAGI Applications with Go
Lefteris Zafiris NTA Ltd
Astricon 2014 Las Vegas

Who we are
VoIP engineer at NTA ltd
Voice and text toolset
- Flite Asterisk App
- eSpeak Asterisk App
- googleTTS
- speech recognition - Google speech API
- Text translation
github.com/zaf

Who we are
NTA Ltd - nta.co.uk
- UK based VoIP provider since 2001
- Hosted PBX services
- SIP
- FOSS
- Kamailio / Asterisk
- Perl

Perl stack
- FastAGI server
- Net::Server
- fork / prefork
- Memory
- Capacity - calls / server

Enter Go
2007 Google
Rob Pike, Ken Thompson, Robert Griesemer
- Statically typed
- Garbage-collected
- Natively compiled
- Concurrency
- C family
- Pragmatic, minimalistic

Enter Go
Do not communicate by sharing memory.
Share memory by communicating.
- Goroutines
lightweight threads
cheap
multiplexed in OS threads
- Channels
communication
synchronization

Enter Go
/*
A simple example in go
*/
package main
import "fmt"
func main() {
var msg string
msg = "Hello Astricon"
// Retroactively say hello to all Astricons!
for i := 0; i <= 10; i++ {
fmt.Println(msg, 2004+i)
}
}

Go toolset
- go command
test
fmt
build
install
- Debugging
gdb
- Package management
go get

AGI Package
- AGI and FastAGI support
- Simple familiar interface
- BSD Licence
- Install:
go get github.com/zaf/agi

AGI Package
- Session structure
AGI environment variables
Env map[string]string
- Reply structure
Numeric result of the AGI command
Res int
Additional returned data
Dat string

AGI Package
- AGI commands as methods of the Session struct
func (a *Session) Answer() (Reply, error)
func (a *Session) SendText(text string) (Reply,
error)
func (a *Session) Hangup(channel ...string)
(Reply, error)
func (a *Session) SayDigits(digit int,
escape string) (Reply, error)

AGI Package usage
- Create a new session:
myAgi := agi.New()
- Initialize, read and parse AGI environment:
myAgi.Init(nil)
- Execute AGI commands:
myAgi.StreamFile("hello-world", "#")

AGI example
package main
import (
"log"
"github.com/zaf/agi"
)
func main() {
// Create a new AGI session and Parse the AGI environment.
myAgi := agi.New()
err := myAgi.Init(nil)
if err != nil {
log.Fatalf("Error Parsing AGI environment: %vn", err)
}
// Print a message on the asterisk console using Verbose.
_, err := myAgi.Verbose("Hello World")
if err != nil {
log.Fatalf("AGI reply error: %vn", err)
}
}

FastAGI Example
func main() {
// Create a tcp listener on port 4573 and start a new goroutine for each connection.
ln, err := net.Listen("tcp", ":4573")
if err != nil {
log.Fatal(err)
}
defer ln.Close()
for {
conn, err := ln.Accept()
if err != nil {
log.Println(err)
continue
}
go connHandle(conn)
}
}

FastAGI Example
func connHandle(c net.Conn) {
defer c.Close()
myAgi := agi.New()
// Create I/O buffers
rw := bufio.NewReadWriter(bufio.NewReader(c), bufio.NewWriter(c))
err := myAgi.Init(rw)
if err != nil {
log.Println(err)
return
}
rep, err := myAgi.StreamFile("hello", "1234567890#*")
if err != nil {
log.Println(err)
return
}
// Check AGI command return value
if rep.Res == -1 {
log.Println("Failed to playback file")
}
}

Error Handling
func connHandle(c net.Conn) {
defer func() {
c.Close()
if err := recover(); err != nil {
log.Println("Session terminated:", err)
}
}()
myAgi := agi.New()
rw := bufio.NewReadWriter(bufio.NewReader(c), bufio.NewWriter(c))
err := myAgi.Init(rw)
checkErr(err)
_, err := myAgi.Verbose("Hello World")
checkErr(err)
}
//Check for AGI Protocol errors or hangups
func checkErr(e error) {
if e != nil {
panic(e)
}
}

AGI Debug
- Error testing
- Performance testing
- Security testing
Eliminate the use of Asterisk
Custom AGI Payloads

Agistress
A client that can connect to servers using the Asterisk Gateway
Interface
- user defined payloads
- user controlled session parameters
- fast - parallel session spawning
- performance measuring
- written in Go
go get github.com/zaf/agistress

Agistress
Run once and display full debug output of the AGI session:
agistress -host 127.0.0.1 -single
Stress test the AGI server by spawning 10 sessions 10 times per
second and display performance details:
agistress -host 127.0.0.1 -sess 10 -runs 10
Run once using custom AGI payload from config file:
agistress -host 127.0.0.1 -single -conf payload.conf

Agistress
Config file:
- JSON format
- Environment variables
- AGI Command replies
- Reply delay

Agistress
Config file sample:
{
"AgiPayload": [
{"Msg": "200 result=0", "Delay": 10},
{"Msg": "200 result=0", "Delay": 10},
{"Msg": "200 result=1 endpos=1234", "Delay": 3000},
{"Msg": "HANGUP"}
]
}

Agistress
Sample output:
Running FastAGI bench against: 192.168.1.10:4573
Press Enter to stop.
A new run each: 100ms
Sessions per run: 10
Reply delay: 50ms
FastAGI Sessions
Active: 20
Completed: 520
Duration: 206121479 ns (last 10000 sessions average)
Failed: 0

Measuring
Comparison between FastAGI implementations:
- Perl:
Asterisk::AGI
Net::Server::PreFork
- Go:
agi package
net package

Measuring
Simple sound file Playback application:
- Start session and parse AGI Env
- Parse FastAGI request URI
agi://10.11.12.13/myagi?file=echo-test
- Check channel status
- Answer channel
- Playback given file
Perl: 73 loc (http://goo.gl/hdsxuw)
Go: 90 loc (http://goo.gl/uxezg7)

Benchmark
Stress test using agistress:
- 1 session/sec
agistress -delay=0
- 25 sessions/sec
agistress -runs=5 -sess=5 -delay=0
- 50 sessions/sec
- 100 sessions/sec
- 200 and 400 sessions/sec

Scaling FastAGI Applications with Go

Benchmark
Memory usage:
Many active sessions
Custom AGI Payload, 5 sec playback duration
- 12 active sessions:
agistress -sess=2 -conf=sample.conf
- 24 active sessions:
agistress -sess=4 -conf=sample.conf
- 48, 96 and 192 sessions

Results
- Up to 3 times less CPU usage
- Up to 2.5 times shorter runtime
- Enormous memory savings

Scaling FastAGI Applications with Go

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