If you are interested in IDE flame wars debating, here it is another brief (10 question) survey about which IDEs are being used, by Genuitec and AvantSoft: What’s Your Favorite IDE and How Well do You Know It?
I have updated the WP-chgFontSize WordPress plugin to fix a nasty bug:
You can download the new version v1.2 at the WordPress Plugins Directory.
Hi there, nice site with good info. I really like coming back here often. There’s only one thing that annoys me and that is the misfunctioning of comment posting. I usually get to 500 error page, and have to do the post twice.
As I am on vacation, I have had some time to read part of the Programming Erlang book I mentioned some posts ago. After reading the firsts chapters, I was surprised to see that one of the not so much mentioned Erlang central features is that relies extremely on the pattern matching idiom. Just one example, the “=” operator is a pattern matching operator, which behaves like assignment when the variable is unbound, and act like a pattern matching expression when it is bound.
Another feature that I was glad to see is the actor model paradigm, with messages sent from and to Actors (like Scala or Smalltalk) to deal with highly complex concurrency models.
But after playing with some of the examples that appear on the book, I found this exercise at the end of the chapter 8 :
Write a ring benchmark. Create N processes in a ring. Send a message round the ring M times so that a total of N * M messages get sent. Time how long this takes for different values of N and M.
Ok, so here it is my solution (ring.erl):
-module (ring).
-export ([start/2]).
start(N, M) ->
statistics(runtime),
statistics(wall_clock),
Main_process = self(),
io:format("Creating ~p ring processes~n", [N]),
spawn(fun() -> ring(1, N, M, self(), Main_process) end),
receive
ended -> void
end,
{_, Time1} = statistics(runtime),
{_, Time2} = statistics(wall_clock),
U1 = Time1,
U2 = Time2,
io:format("Ring benchmark for ~p processes and ~p messages =
~p (~p) milliseconds~n", [N, M, U1, U2]).
ring(_, N, _, _, _) when(N =< 0)->
io:format("Empty ring~n"),
erlang:error(emptyRing);
ring(_, _, M, _, _) when(M =< 0)->
io:format("No messages to send~n"),
erlang:error(noMessagesToSend);
ring(N, N, M, First_process, Main_process) ->
io:format("Ring process ~p (~p) created~n", [N, self()]),
io:format("Sending ~p messages through the ring~n", [M]),
First_process ! {send, main_process, Main_process},
loop(M, N, N, First_process, Main_process);
ring(I, N, M, First_process, Main_process) ->
io:format("Ring process ~p (~p) created~n", [I, self()]),
Next_process = spawn(fun() ->
ring(I+1, N, M, First_process, Main_process) end),
loop(M, I, N, Next_process, Main_process).
loop(0, N, N, _, Main_process) ->
io:format("Ring process ~p (~p) finished~n", [N, self()]),
Main_process ! ended;
loop(0, I, _, _, _) ->
io:format("Ring process ~p (~p) finished~n", [I, self()]);
loop(M, I, N, Next_process, Main_process) ->
receive
{send, From, From_process} ->
io:format("Process ~p (~p) received message ~p
from process ~p (~p) ~n", [I, self(), M, From, From_process]),
Next_process ! {send, I, self()},
loop(M-1, I, N, Next_process, Main_process)
end.
And here the benchmark results based on Erlang R11B, two different configuration machines and running the above code but without I/O (ring_noio.erl):
The exercise illustrates how long it takes to spawn a large number of processes and the cost of message passing between them. There is no parallelism in this exercise, as there is only one process active at a time (the others are waiting for a message), but demonstrates how well Erlang can deal with lots of processes and lots of sending and receiving messages. Although I believe I need to do more serious tests, creating 10.000 process and passing 100 million messages in 35 seconds is a great mark.
The second part of the exercise is to write a similar program in some other programming language and to compare the results. Check these links to see some results:
Next chapters: distributed programming, OTP and Mnesia (the Erlang Database).
Your solution is clearer to me than the one over at http://muharem.wordpress.com/ though I found that a very interesting article, too.
Thanks for this. I’m working my way through the book v-e-r-y slowly as coming from a purely flash development background almost all Erlang concepts are new on me.
But, damn, there’s just something about erlang that makes me want to learn it!
Please have a look at my version:
http://philemonworks.wordpress.com/2008/05/23/ring-benchmark-my-first-concurrent-erlang/
I did not spend much time on gathering significant statistics. Getting a readable compact program was far more challenging.
Hello,
The following implementation in C# using Rx.NET runs in 1min58 in LINQPad on quad core Q6600@2.4ghz:
var listeners =
Enumerable.Range(0, 10000)
.Select(_ => new Subject(Scheduler.TaskPool))
.MemoizeAll();
listeners.Publish(o => o.Zip(o.Skip(1), (l, r) => new { l, r}))
.Run(o => o.l.Subscribe(o.r));
Observable
.Range(0, 10000)
.Delay(TimeSpan.FromMilliseconds(1000))
.Subscribe(listeners.First());
listeners.Last().Last().Dump();
I also have the following F# implementation running in 50s on the same machine (F# interactive):
type Agent = MailboxProcessor
let count = 10000
let now = System.DateTime.Now
Agent.Start (fun inbox ->
async {
while true do
let! msg = inbox.Receive()
if msg = count then
printfn “%A” (System.DateTime.Now – now).TotalMilliseconds })
|> Seq.unfold (fun next ->
let agent = Agent.Start (fun inbox ->
async {
while true do
let! msg = inbox.Receive()
next.Post msg } )
Some (agent, agent))
|> Seq.nth count
|> (fun agent -> for i in 1..count do agent.Post i)
Both code seems to scale pretty well versus the timing I had on my dual core laptop at work (T7400), although I only remember the time for the C#-Rx version at 5min50.
David
Haven’t had time to write about it, still, better late than never.
I have always heard positive experiences from people switching to Mac. Last month, forced by the slowing down of my Acer TravelMate 290 laptop and encouraged by Andy Piper and Eneko Alonso, who had blogged their recent switching experiences, I finally bought a 15” MacBook Pro and a Mighty Mouse from Apple.
Despite there is always a bit of a learning curve involved (I have had some minor issues due to Windows-Mac equivalent keys, as the Print Screen, Control and Command, and Alt and Options keys), I found the move very easy. Setting up Mac OS X is really simple, and the user interface behavior is terrific. I have also found the blogosphere as a very valuable aid for switchers, as it is plenty of useful tips and hints. I recommend you How to Switch to the Mac and Andy Piper’s Mac posts.
After playing with some applications that I have found at some Mac specialized web sites as MacUpdate, here is the list of them that I have installed so far:
Anyway, as a Mac beginner user, your tips will be welcomed.
I’d recommend jUploadr rather than Flickr Uploader – it is far, far richer in function. other than that, I’m pretty much using the same stuff as you, except for those tools I don’t need (blackberry, Parallels, etc.).
You might find the Textmate book helpful.
And thanks for referencing my posts! I’m glad you found them useful.
I’ve found iusethis.com for a source of popular apps and such. Off the top of my list would be the Unsanity products HERE, of course, as you’ve listed it already, Flip4Mac, iBackup, info.xhead, and another one by the Flip4Mac people, Drive In.
Andy, Antonio, thanks for the recommendations!
welcome to the dark side, ferdy. It’s nice here. 🙂
