[erlang-questions] How to Name Concurrency Patterns

Ludovic Demblans <>
Wed Feb 19 23:48:05 CET 2014


I have no idea but i suggest to look for names in people's real life.  
People can quickly recognize situations they see everyday. The Travelling  
salesman problem has nothing to do with selling something but it's easy to  
understand (at least the problem, maybe not the maths).

Like, map(F,L) with maximum concurrent processes could be easily explained  
in terms of checking out at a supermarket :) (ok, not very sexy)

My two cents.


Le Wed, 19 Feb 2014 23:20:55 +0100, aman mangal <> a  
écrit:

> zeromq has a long list of queuing models-
>
> http://zguide.zeromq.org/page:all
>  http://api.zeromq.org/4-0:zmq-socket
>
> Aman Mangal
> 4th year Undergraduate Student
> Department of Computer Science & Engineering
> IIT Bombay
> www.cse.iitb.ac.in/~amanmangal
>
>
> On Thu, Feb 20, 2014 at 3:40 AM, Joe Armstrong <> wrote:
>
>> Very Nice
>>
>> More like this please.
>>
>> /Joe
>>
>>
>> On Wed, Feb 19, 2014 at 11:08 PM, Dmitry Kolesnikov <
>> > wrote:
>>
>>> Hello,
>>>
>>> Long time ago, I was looking into async message queue patters.
>>> I found namomsg tutorial is very nice it depicts most common patterns
>>> http://tim.dysinger.net/posts/2013-09-16-getting-started-with-nanomsg.html
>>>
>>>
>>>
>>> Best Regards,
>>> Dmitry
>>> >-|-|-(*>
>>>
>>> > On 19 Feb 2014, at 23:14, Joe Armstrong <> wrote:
>>> >
>>> >
>>> >
>>> > Hello, I'm giving a course in distributed and parallel programming in
>>> > Erlang ...
>>> >
>>> > Next week I'll be talking about common concurrency patterns, I was
>>> > talking with the course adviser, and I rattled off the names of a few
>>> > concurrency patterns that were well-known and easy to explain. I said
>>> > I'll do PUB-SUB, pipeline, map-reduce, parallel map, and so on.
>>> >
>>> > At this stage the course adviser said that a) things like PUB-SUB
>>> > would not be familiar to the students and that b) It would take more
>>> > than 5-10 minutes to explain PUB_SUB.
>>> >
>>> > At this stage I thought "pity these patterns don't have well-known
>>> > names".
>>> >
>>> > What I'd like is to make a catalog of "well-known" concurrency
>>> > patterns.  I'd like to name them, and describe them informally, and
>>> > give the example code in Erlang.
>>> >
>>> > For example, here's how I might describe PUB-SUB.
>>> >
>>> > == PUB-SUB
>>> >
>>> >    - There are a number of named channels
>>> >    - You can post messages to a channel ie Publish the message (the  
>>> PUB)
>>> >    - You can subscribe to a channel (The SUB)
>>> >    - If you are currently subscribed to a channel you will be sent  
>>> all
>>> messages
>>> >      sent to the channel.
>>> >
>>> > A rudimentary version of this is about 25 lines of Erlang. A full
>>> > version with load balancing, removing bottlenecks etc. would be a lot
>>> > longer, but that's not the point. The basic concurrent structure can
>>> > be explained in a few lines and named.
>>> >
>>> >
>>> > Pipeline is another example: The output of the first process is the
>>> > input to the next process and so on...
>>> >
>>> > Now I start having problems.
>>> >
>>> > Suppose I want to generalize a regular map.
>>> >
>>> > To be precise. Suppose map(F, L) means [F(I) || I <- L]
>>> >
>>> > pmap(F, L) is parallel map (easy) all the F(I)'s are computed
>>> concurrently.
>>> >
>>> > pmap(F, L, Max) behaves like map(F,L) with at most Max F(I)'s  
>>> computed
>>> concurrently.
>>> >
>>> > What should this be called? "Pool of workers"
>>> >
>>> > There seem to be things with well-known names "Load-balancer"
>>> "map-reduce" etc.
>>> >
>>> > Then there are things that we know of but that are not named. For
>>> > example my DNS resolver has two DNS names DNS1 and DNS2.  If DNS1 is
>>> > broken the resolver tries DNS2 - what is concurrency pattern called
>>> > (Pool of responders) or what?
>>> >
>>> > The other day I suggested that for fault tolerance it was much easier
>>> > to let the client go to multiple machines rather than use an  
>>> expensive
>>> > load balancer and fail-over system on the server - but there was no
>>> > convenient name to capture this idea.
>>> >
>>> > There sees to be no accepted terminology here - so I'd appreciate any
>>> > suggestions you have as to the names of common currency patterns that
>>> > you use together with definitions of what the names mean.
>>> >
>>> > Cheers
>>> >
>>> > /Joe
>>> >
>>> > _______________________________________________
>>> > erlang-questions mailing list
>>> > 
>>> > http://erlang.org/mailman/listinfo/erlang-questions
>>>
>>
>>
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>> 
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>>
>>


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