review of std.parallelism

[Michel Fortin]

On 2011-03-19 14:14:51 -0400, Michel Fortin <michel.fortin at michelf.com> said:

> I'm not too convinced about the "I know what I'm doing" argument when I 
> look at this example from asyncBuf's documentation:
> 
>     auto lines = File("foo.txt").byLine();
>     auto duped = map!"a.idup"(lines);  // Necessary b/c byLine() 
> recycles buffer
> 
>     // Fetch more lines in the background while we process the lines already
>     // read into memory into a matrix of doubles.
>     double[][] matrix;
>     auto asyncReader = taskPool.asyncBuf(duped);
> 
>     foreach(line; asyncReader) {
>         auto ls = line.split("\t");
>         matrix ~= to!(double[])(ls);
>     }
> 
> Look at the last line of the foreach. You are appending to a non-shared 
> array from many different threads. How is that not a race condition?

... or maybe I just totally misunderstood asyncBuf. Rereading the 
documentation I'm under the impression I'd have to write this to get 
what I expected:

	foreach (line; parallel(asyncReader))
		...

And that would cause a race condition. If that's the case, the example 
is fine. Sorry for the misunderstanding.

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/