Thinking in a Highly Concurrent, Mostly-functional Language

Transcription

1 Thinking in a Highly Concurrent, Mostly-functional Language Build Stuff Vilnius, November 19th 2014 Francesco Cesarini Founder & Technical francesco@erlang-solutions.com

2 Thinking in a Highly Concurrent, Mostly-functional Language Erlang Training and Consulting Ltd QCON London, March 12 th, 2009 Francesco Cesarini francesco@erlang-consulting.com

3 counter_loop(count) -> receive increment -> counter_loop(count + 1); {count, To} -> To! {count, Count}, counter_loop(count) end. Erlang

4 Tim Bray, Director of Web Technologies Sun Microsystems

5 Tim Bray, Director of Web Technologies Sun Microsystems

6 Syntax

7 Concurrency

8 Erlang Highlights: Concurrency Creating a new process using spawn -module(ex3). -export([activity/3]). activity(name,pos,size) -> activity(joe,75,1024) Pid = spawn(ex3,activity,[joe,75,1024])

9 Erlang Highlights: Concurrency Processes communicate by asynchronous message passing Pid! {data,12,13} receive {start} -> {stop} -> {data,x,y} -> end

10 Products: AXD301 Switch A Telephony-Class, scalable ( GBps) ATM switch Designed from scratch in less than 3 years AXD 301 Success factors:! Competent organisation and people! Efficient process! Excellent technology (e.g. Erlang/OTP)

11 Products: AXD301 Switch Erlang: ca 1.5 million lines of code! Nearly all the complex control logic! Operation & Maintenance! Web server and runtime HTML/ JavaScript generation C/C++: ca 500k lines of code! Third party software! Low-level protocol drivers! Device drivers Java: ca 13k lines of code! Operator GUI applets

12 Concurrency Modeling Model for the natural concurrency in your problem In the old days, processes were a critical resource! Rationing processes led to complex and unmanageable code Nowadays, processes are very cheap: if you need a process create one! Example: AXD301 process model 1 st prototype: 6 processes/call 2 processes/call 1 process/all calls 2 processes/ call transaction 4-5 processes/ call transaction

13 1+1 Redundancy Good ol Telecoms ~ calls per processor pair Stable-state replication No ongoing sessions lost at failover Active Standby Control plane User plane Control signalling Device board Data path

14 First IM Proxy Prototype sockets multiplexing de-multiplexing state/error handling de-multiplexing sockets multiplexing listener users

15 First IM Proxy Prototype sockets supervisor multiplexing state/error handling simple 1-1 de-multiplexing sockets multiplexing listener users

16 Products: EjabberD IM Server A distributed XMPP server Started as an Open Source Project by Alexey Shchepin Commercially Supported by Process-One (Paris)! 40% of the XMPP IM market! Used as a transport layer! Managed 30,000 users / node

17 Products: EjabberD IM Server A distributed XMPP server Started as an Open Source project by Alexey Shchepin Commercially Supported by Process-One (Paris)! 40% of the XMPP IM market! Used as a transport layer! 2008, Managed 30,000 users / node MongooseIM is a fork and rewrite! Open Source, supported by Erlang Solutions! Used for Messaging and Device Management! 2014, managed 1 million users / node

18 Fully Replicated Cluster Ejabberd 2002 Client must re-connect if one of its session handlers dies s2s muc Load balancer s2s c2s muc sm c2s sm s2s c2s muc sm Fully replicated Mnesia database

19 Share-nothing Architecture Messaging Gateway

20 Share-nothing Architecture Messaging Gateway Router/FE Router/FE Router/FE Router/FE POP SMTP IMAP... tunnel POP SMTP IMAP... tunnel POP SMTP IMAP... HTTP HTTP DBMS

21 Erlang Concurrency Under Stress Pre-SMP 100% CPU Throughput / Second Line 1 Balanced Erlang System Line 2 Erlang System with bottle necks Simultaneous Requests

22 Erlang Concurrency Under Stress Pre-SMP YAWS Throughput (KBytes/second) Simultaneous Requests

23 Erlang Concurrency Under Stress Post-SMP

24 Stress Tests With SMP I/O Starvation TCP/IP Congestion Memory Spikes Timeout Fine-tuning OS Limitations ERTS Configuration Flags Shut down Audit Logs

25 SMP bottlenecks pre 2008

26 SMP bottlenecks post 2008 Erlang VM Scheduler #1 run queue Scheduler #2 run queue migration logic Scheduler #N run queue

27 Big Bang Benchmark post 2008 "

28 Mandelbrot "

29 Now for the Bottlenecks "

30 Now for the Bottlenecks "

31 Now for the Bottlenecks

32 Now for the Bottlenecks

33 Now for the Bottlenecks

34 Riak and other scalable architectures

35 N/R/W Values Erlang Erlang Solutions Ltd Solutions Ltd

36 N/R/W Values Erlang Erlang Solutions Ltd Solutions Ltd

37 Clusters and SD Erlang

38 Release Statement of Aims To scale the radical concurrency-oriented programming paradigm to build reliable general-purpose software, such as serverbased systems, on massively parallel machines (10^5 cores).!!!!!!"

39 Release Limitations exist on all levels. You would not want an Erlang VM to run with 10^5 schedulers.!!!!!!"

40 Release Push the responsibility for scalability from the programmer to the VM Analyze performance and scalability Identify bottlenecks and prioritize changes and extensions Tackle well-known scalability issues Ets tables (shared global data structure) Message passing, copying and frequently communicating processes

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42 Discount Code: authd 50% off the Early Release 40% off the printed copy