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Can we move beyond threads and locks to manage concurrency? Are there more advanced models than threads and locks? How do other languages manage the concurrency? We see some examples in others languages and a possible solution in C++. Example code: https://github.com/italiancpp/meetup-milano-2014/tree/master/cpp_actor_model
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C++ Actor ModelYou’ve Got Mail ...
Italian C++ Community
Why are we here?
Italian C++ Community
std::thread/async, isn’t it enough?
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std::thread/async, isn’t it enough?
Example code: double_poll
Poll Left Poll Right
Thread 1 Thread 2
Acc
Increment
Add Add
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Concurrency model
- Single Thread → Node.js
- Actor Model → Erlang
- CSP → GO
- STM → Clojure
- etc ...
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Node.js
It’s simple
One thread
Asynchronous I/O (event-loop)
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Node.js - Examples
var fs = require("fs");
fs.readFile('/etc/passwd', function (err, data) { if (err) throw err; console.log("-> " + data + " <-");});
----
var http = require('http');
http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/plain'}); res.end('Hello World\n');}).listen(1337, "127.0.0.1");
console.log('Server running at http://127.0.0.1:1337/');
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Node.js - Is it fast?
ab -n 10000 -c 1000 http://127.0.0.1:1337/
Time taken for tests: 1.283 secondsComplete requests: 10000Total transferred: 1130000 bytesRequests per second: 7797.21 [#/sec] (mean)Time per request: 128.251 [ms] (mean)Time per request: 0.128 [ms] (mean, across all concurrent requests)Transfer rate: 860.43 [Kbytes/sec] received
Connection Times (ms) min mean[+/-sd] median maxConnect: 0 58 232.7 0 1000Processing: 5 20 27.1 13 420Waiting: 5 20 27.1 13 420Total: 13 78 246.5 13 1234
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Node.js - Is it fast?
YES!!!
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Concurrency model
Single Thread → Node.js (Good)
Can we do better?
Copy from others ...
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ErlangErlang is a programming language used to build massively scalable soft real-time systems with requirements on high availability.
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Actor Model
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A model of concurrent computation that treats "actors" as the primitives and fundamental units of computation.
Actor Model
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Actor Model
It should embody three properties:
● Processing → Can do something● Storage → Can remember something● Communication → Can communicate with
others
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Actor Model
In an actors system:
● Everything is an actor ● An actor is an entity that sends, receives
messages● An actor is an entity with a behaviour
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In response to a message that it receives, an actor can:
● create more actors● send messages to other actors ● determine how to respond to the next
message received
Actor Model
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Actor Model
A1
A3
M1
A21
A22
A23
M2
M3
A2
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Actor Model
Does it work?
Is it fast?
Italian C++ Community
Erlang - Resultsab -n 10000 -c 1000 http://127.0.0.1:8080/
Time taken for tests: 0.538 secondsComplete requests: 10000Total transferred: 1300000 bytesRequests per second: 18604.20 [#/sec] (mean)Time per request: 53.751 [ms] (mean)Time per request: 0.054 [ms] (mean, across all concurrent requests)Transfer rate: 2361.86 [Kbytes/sec] received
Connection Times (ms) min mean[+/-sd] median maxConnect: 0 10 4.8 10 27Processing: 7 16 4.8 16 39Waiting: 5 13 4.2 13 34Total: 8 26 8.3 26 59
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Erlang vs Node.js - ResultsNode.js
Time taken for tests: 1.461 secondsTotal transferred: 1140000 bytesRequests per second: 6843.55 [#/sec]Time per request: 146.123 [ms]Time per request: 0.146 [ms]Transfer rate: 761.88 [Kbytes/sec]
Connection Times (ms) min mean[+/-sd] median maxConnect: 0 59 234.5 0 1001Processing: 8 22 40.7 14 443Waiting: 7 22 40.7 14 443Total: 10 81 262.9 14 1443
Erlang
Time taken for tests: 0.538 secondsTotal transferred: 1300000 bytesRequests per second: 18604.20 [#/sec]Time per request: 53.751 [ms] Time per request: 0.054 [ms] Transfer rate: 2361.86 [Kbytes/sec]
Connection Times (ms) min mean[+/-sd] median maxConnect: 0 10 4.8 10 27Processing: 7 16 4.8 16 39Waiting: 5 13 4.2 13 34Total: 8 26 8.3 26 59
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Actor Model - Is it Fast?
YES!!!
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Erlang - Example
https://github.com/extend/cowboy
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C++ - Actor model
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C++ library
● http://neverlord.github.io/libcppa/ - Erlang inspired● http://www.theron-library.com/ - No fault - No Event IO● https://code.google.com/p/actor-cpp/source/list - Not developed since
2012● https://code.google.com/p/libactor/ - Right now it is usable, although it
may not be ready for production● https://casablanca.codeplex.com/ - Removed actor?!?!● http://www.stdthread.co.uk/ - No OSS
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libcppa - Features
● Lightweight actor implementations● Pattern matching for messages ● Error handling based on Erlang’s failure
model● etc ..
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libcppa - Is it enough?
Can it solve the initial problem?
example code: double_poll_actor
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libcppa - Is it enough?
Main
Poll Left
Poll Right
Acc
poll
poll
at
incLeft
incRight
inc
beast
beast
threshold
fire
fire
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libcppa - Actor == thread?
How many actors can I spawn?
A lot!!!!
example code: how_many_actors
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libcppa - Errors
● Isolated ● Linked● Monitored
example code: err_mng
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libcppa - I/O - brokers
A broker is an event-based actor running in the middleman that multiplexes socket I/O
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libcppa - I/O - brokers
● Create in particular way● Receive special messages from “system”● Can take ownership of given connection
example code: http_actor
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libcppa - Is it fast???
ab -n 10000 -c 1000 http://127.0.0.1:1339/
Time taken for tests: 0.438 secondsComplete requests: 10000Total transferred: 1480000 bytesRequests per second: 22848.00 [#/sec] (mean)Time per request: 43.767 [ms] (mean)Time per request: 0.044 [ms] (mean, across all concurrent requests)Transfer rate: 3302.25 [Kbytes/sec] received
Connection Times (ms) min mean[+/-sd] median maxConnect: 1 5 5.6 3 26Processing: 1 6 5.9 4 222Waiting: 1 4 4.8 3 221Total: 3 11 10.6 7 231
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libcppa vs Erlang - Resultslibcppa
Time taken for tests: 0.438 secondsTotal transferred: 1480000 bytesRequests per second: 22848.00 [#/sec] Time per request: 43.767 [ms]Time per request: 0.044 [ms]Transfer rate: 3302.25 [Kbytes/sec]
Connection Times (ms) min mean[+/-sd] median maxConnect: 1 5 5.6 3 26Processing: 1 6 5.9 4 222Waiting: 1 4 4.8 3 221Total: 3 11 10.6 7 231
Erlang
Time taken for tests: 0.538 secondsTotal transferred: 1300000 bytesRequests per second: 18604.20 [#/sec]Time per request: 53.751 [ms] Time per request: 0.054 [ms] Transfer rate: 2361.86 [Kbytes/sec]
Connection Times (ms) min mean[+/-sd] median maxConnect: 0 10 4.8 10 27Processing: 7 16 4.8 16 39Waiting: 5 13 4.2 13 34Total: 8 26 8.3 26 59
Italian C++ Community
libcppa - Is it fast???
YES!!!
Italian C++ Community
Actor Model
Gianluca PadovaniSW craftsmanship, TDD addicted, agile coach. I like Ruby, NodeJs and everything is interesting. I also work a lot on C#, C++. I like to code, a lot :-)https://www.linkedin.com/pub/gianluca-padovani/2/261/a92
https://twitter.com/GPad619
https://github.com/gpad
http://www.slideshare.net/gpadovani
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Reference● Carl Hewitt's Homepage● Hewitt, Meijer and Szyperski: The Actor Model● Takeaways from Hewitt, Meijer and Szyperski’s talk on the Actor model● https://github.com/Neverlord/libcppa● http://libcppa.blogspot.de/● Dominik Charousset and Matthias Vallentin: libcppa -- Designing an Actor
Semantic for C++11● https://github.com/mavam/vast● Learn you some Erlang● https://github.com/extend/cowboy● Actors are not a good concurrency model● Seven Languages in Seven Weeks: A Pragmatic Guide to Learning
Programming Languages
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Actor Model
Thank You!
