Re: dmd 1.045 / 2.030 release

[Robert Jacques]

On Tue, 12 May 2009 12:41:50 -0400, dsimcha <dsim...@yahoo.com> wrote:
== Quote from Tomas Lindquist Olsen (tomas.l.ol...@gmail.com)'s article
Is there a reason for the missing announcement ?
http://digitalmars.com/d/1.0/changelog.html#new1_045
http://www.digitalmars.com/d/2.0/changelog.html#new2_030
and what happened to 1.044 ?
-Tomas

Probably because it doesn't quite work yet.  I'm waiting for some crufty  
old 2.029
code to run, so I thought I'd try out shared a little.  Here are the  
results:

import std.stdio, std.perf, core.thread;

shared uint foo;

void main() {
    auto t = new Thread({stuff();});
    t.start;
    scope pc = new PerformanceCounter;
    pc.start;
    foreach(i; 0..10_000_000) {
        foo++;
    }
    t.join;
    pc.stop;
    writeln(pc.milliseconds);
    uint bar = foo;
    writeln(bar);  // Prints some pseudorandom, wrong number.
}

void stuff() {
    foreach(i; 0..10_000_000) {
        foo++;
    }
}

Or is the automatic synchronization of shared variables part not  
supposed to be
implemented yet?

Bartosz hasn't talked about D's shared system yet. Anyways, what you are  
seeing is a classic read/write race, and is expected even if foo is  
sequential consistent or locked. What you'd need to test is the Peterson  
lock  
(http://bartoszmilewski.wordpress.com/2008/11/11/who-ordered-sequential-consistency/)

Remember foo++ ->
r1 = foo;
r1++;
foo = r1;

So
lock(foo);
r1 = foo;
unlock(foo);
r1++;
lock(foo);
foo = r1;
unlock(foo);