Code:
    import std.concurrency;
    import core.thread;
    //import vibe.http.client;      // If uncommented this line, the thread "worker" does not start
    void worker() {
        foreach (i; 0 .. 5) {
            Thread.sleep(500.msecs);
            writeln(i, " (worker)");
        }
    }

    void main() {
        spawn(&worker);

        foreach (i; 0 .. 5) {
            Thread.sleep(300.msecs);
            writeln(i, " (main)");
        }

        writeln("main is done.");
    }

How to launch threads with vibe.d? It doesn't work at both compilers.

- Gentoo Linux 64
- DMD64 D Compiler v2.069.0 (dub dependency)
- DMD64 D Compiler v2.071.0
- dub-0.9.24 USE="dmd-2_069"

dub.json:
{
  "name" : "axt-threads-json",
  "description" : "A minimal D bundle.",
  "targetType": "executable",
  "targetPath": "bin",
  "dependencies" : {
      "vibe-d": "~>0.7.28",
  },
  "configurations": [
            {
                "name": "Debuger"
            },
            {
                "name": "Release"
            }
    ]
}

On Wednesday, 27 April 2016 at 13:00:29 UTC, RuZzz wrote:
> Code:
>     import std.concurrency;
>     import core.thread;
>     //import vibe.http.client;      // If uncommented this line, the thread "worker" does not start
>     void worker() {
>         foreach (i; 0 .. 5) {
>             Thread.sleep(500.msecs);
>             writeln(i, " (worker)");
>         }
>     }
>
> [...]

you should use the built in concurrency primitives vibe.d offers.
especially runTask and runWorkerTask.
see the vibe.d examples and http://vibed.org/features

On Wednesday, 27 April 2016 at 13:00:29 UTC, RuZzz wrote:
> Code:
>     import std.concurrency;
>     import core.thread;
>     //import vibe.http.client;      // If uncommented this line, the thread "worker" does not start
>     void worker() {
>         foreach (i; 0 .. 5) {
>             Thread.sleep(500.msecs);
>             writeln(i, " (worker)");
>         }
>     }
>
>     void main() {
>         spawn(&worker);
>
>         foreach (i; 0 .. 5) {
>             Thread.sleep(300.msecs);
>             writeln(i, " (main)");
>         }
>
>         writeln("main is done.");
>     }
>
> How to launch threads with vibe.d? It doesn't work at both compilers.

You don't. vibe.d uses fibers (aka green threads).

On Wednesday, 27 April 2016 at 23:30:10 UTC, Nicholas Wilson wrote:
> On Wednesday, 27 April 2016 at 13:00:29 UTC, RuZzz wrote:
>> Code:
>>     import std.concurrency;
>>     import core.thread;
>>     //import vibe.http.client;      // If uncommented this line, the thread "worker" does not start
>>     void worker() {
>>         foreach (i; 0 .. 5) {
>>             Thread.sleep(500.msecs);
>>             writeln(i, " (worker)");
>>         }
>>     }
>>
>>     void main() {
>>         spawn(&worker);
>>
>>         foreach (i; 0 .. 5) {
>>             Thread.sleep(300.msecs);
>>             writeln(i, " (main)");
>>         }
>>
>>         writeln("main is done.");
>>     }
>>
>> How to launch threads with vibe.d? It doesn't work at both compilers.
>
> You don't. vibe.d uses fibers (aka green threads).

That doesn't matter. Native threads should work just fine, I'm using them without problems in a vibe.d app.

Could it be that your main() function is never called at all? Try to insert a writeln() at the beginning. If so, this could be related to the "VibeDefaultMain" setting, see here:
http://vibed.org/docs#custom-main