Calling D from Python. I have two functions in D, compiled to a shared object on Linux using LDC (but I get same problem using DMD).

The sequential code:

    extern(C)
    double sequential(const int n, const double delta) {
      Runtime.initialize();
      const pi = 4.0 * delta * reduce!(
            (double t, int i){ immutable x = (i - 0.5) * delta; return t + 1.0 / (1.0 + x * x); })(
            0.0, iota(1, n + 1));
      Runtime.terminate();
      return pi;
    }

works entirely fine. However the "parallel" code:

    extern(C)
    double parallel(const int n, const double delta) {
      Runtime.initialize();
      const pi = 4.0 * delta * taskPool.reduce!"a + b"(
          map!((int i){ immutable x = (i - 0.5) * delta; return 1.0 / (1.0 + x * x); })(iota(1, n + 1)));
      Runtime.terminate();
      return pi;
    }

causes an immediate segfault (with LDC and DMD.  I am assuming that the problem is the lack of initialization of the std.parallelism module and hence the use of taskPool is causing a problem. I am betting I am missing something very simple about module initialization, and that this is not actually a bug.

Anyone any proposals?

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Saturday, 19 September 2015 at 10:45:22 UTC, Russel Winder wrote:
> Calling D from Python. I have two functions in D, compiled to a shared object on Linux using LDC (but I get same problem using DMD).
>
> [...]

I heard it crashed during the talk. Bummer. I should really be there, seeing as I live about 15 mins away. If you get a chance to talk to Alex Bishop, don't be too harsh on D to him, I'm trying to convince him to make the switch :)

On Saturday, 19 September 2015 at 10:45:22 UTC, Russel Winder wrote:
> Calling D from Python. I have two functions in D, compiled to a shared object on Linux using LDC (but I get same problem using DMD).
>
> The sequential code:
>
>     extern(C)
>     double sequential(const int n, const double delta) {
>       Runtime.initialize();
>       const pi = 4.0 * delta * reduce!(
>             (double t, int i){ immutable x = (i - 0.5) * delta; return t + 1.0 / (1.0 + x * x); })(
>             0.0, iota(1, n + 1));
>       Runtime.terminate();
>       return pi;
>     }
>
> works entirely fine. However the "parallel" code:
>
>     extern(C)
>     double parallel(const int n, const double delta) {
>       Runtime.initialize();
>       const pi = 4.0 * delta * taskPool.reduce!"a + b"(
>           map!((int i){ immutable x = (i - 0.5) * delta; return 1.0 / (1.0 + x * x); })(iota(1, n + 1)));
>       Runtime.terminate();
>       return pi;
>     }
>
> causes an immediate segfault (with LDC and DMD.  I am assuming that the problem is the lack of initialization of the std.parallelism module and hence the use of taskPool is causing a problem. I am betting I am missing something very simple about module initialization, and that this is not actually a bug.
>
> Anyone any proposals?

Try using an explicit TaskPool and destroying it with scope(exit).


Also if using LDC, you can use global ctor/dtor to deal with the runtime.


----------------------->8---------------------

       extern (C) {
            pragma(LDC_global_crt_ctor, 0)
            void initRuntime()
            {
                import core.runtime;
                Runtime.initialize();
            }
            pragma(LDC_global_crt_dtor, 0)
            void deinitRuntime()
            {
                import core.runtime;
                Runtime.terminate();
            }
        }

----------------------->8---------------------

On Sat, 2015-09-19 at 12:21 +0000, ponce via Digitalmars-d-learn wrote:
> […]
> 
> Try using an explicit TaskPool and destroying it with scope(exit).
> 
> 
> Also if using LDC, you can use global ctor/dtor to deal with the runtime.
> 
> 
> ----------------------->8---------------------
> 
>         extern (C) {
>              pragma(LDC_global_crt_ctor, 0)
>              void initRuntime()
>              {
>                  import core.runtime;
>                  Runtime.initialize();
>              }
>              pragma(LDC_global_crt_dtor, 0)
>              void deinitRuntime()
>              {
>                  import core.runtime;
>                  Runtime.terminate();
>              }
>          }
> 
> ----------------------->8---------------------
> 

Hummm… I now do not get a segfault, and the code runs as expected :
-))))) but the program never terminates. :-(

Also, what would I need to cover the DMD and the GDC situations?

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Saturday, 19 September 2015 at 15:42:15 UTC, Russel Winder wrote:
>
> Hummm… I now do not get a segfault, and the code runs as expected :
> -))))) but the program never terminates. :-(

Where is it stuck?

>
> Also, what would I need to cover the DMD and the GDC situations?

I don't know. :(

On Sat, 2015-09-19 at 15:58 +0000, ponce via Digitalmars-d-learn wrote:
> On Saturday, 19 September 2015 at 15:42:15 UTC, Russel Winder wrote:
> > 
> > Hummm… I now do not get a segfault, and the code runs as
> > expected :
> > -))))) but the program never terminates. :-(
> 
> Where is it stuck?

I commented out the :

  //pragma(LDC_global_crt_dtor, 0)
  //void deinitRuntime() {
  //import core.runtime: Runtime;
  //Runtime.terminate();
  //}

and it now works fine :-)))))

> > 
> > Also, what would I need to cover the DMD and the GDC situations?
> 
> I don't know. :(

Let's hope DMD and GDC folk chip in :-)


Sadly the:

 pragma(LDC_global_crt_ctor, 0)
    void initRuntime() {
      import core.runtime: Runtime;
      Runtime.initialize();
   }

will not compile under DMD :-(

-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Saturday, 19 September 2015 at 12:21:02 UTC, ponce wrote:
> On Saturday, 19 September 2015 at 10:45:22 UTC, Russel Winder wrote:
>> Calling D from Python. I have two functions in D, compiled to a shared object on Linux using LDC (but I get same problem using DMD).
>>
>> The sequential code:
>>
>>     extern(C)
>>     double sequential(const int n, const double delta) {
>>       Runtime.initialize();
>>       const pi = 4.0 * delta * reduce!(
>>             (double t, int i){ immutable x = (i - 0.5) * delta; return t + 1.0 / (1.0 + x * x); })(
>>             0.0, iota(1, n + 1));
>>       Runtime.terminate();
>>       return pi;
>>     }
>>
>> works entirely fine. However the "parallel" code:
>>
>>     extern(C)
>>     double parallel(const int n, const double delta) {
>>       Runtime.initialize();
>>       const pi = 4.0 * delta * taskPool.reduce!"a + b"(
>>           map!((int i){ immutable x = (i - 0.5) * delta; return 1.0 / (1.0 + x * x); })(iota(1, n + 1)));
>>       Runtime.terminate();
>>       return pi;
>>     }
>>
>> causes an immediate segfault (with LDC and DMD.  I am assuming that the problem is the lack of initialization of the std.parallelism module and hence the use of taskPool is causing a problem. I am betting I am missing something very simple about module initialization, and that this is not actually a bug.
>>
>> Anyone any proposals?
>
> Try using an explicit TaskPool and destroying it with scope(exit).
>
>
> Also if using LDC, you can use global ctor/dtor to deal with the runtime.
>
>
> ----------------------->8---------------------
>
>        extern (C) {
>             pragma(LDC_global_crt_ctor, 0)
>             void initRuntime()
>             {
>                 import core.runtime;
>                 Runtime.initialize();
>             }
>             pragma(LDC_global_crt_dtor, 0)
>             void deinitRuntime()
>             {
>                 import core.runtime;
>                 Runtime.terminate();
>             }
>         }
>
> ----------------------->8---------------------

What is the difference between shared static this and the global constructor ?  Russell, if you use shared static this for dmd does it work ?  Laeeth.

On Saturday, 19 September 2015 at 16:25:28 UTC, Laeeth Isharc wrote:
>
> What is the difference between shared static this and the global constructor ?  Russell, if you use shared static this for dmd does it work ?  Laeeth.

Would like to know too. On OSX I've found that shared static this() was called by Runtime.initialize(), maybe it's different on Linux.

On Sat, 2015-09-19 at 11:07 +0000, John Colvin via Digitalmars-d-learn wrote:
> 
[…]
> I heard it crashed during the talk. Bummer. I should really be there, seeing as I live about 15 mins away. If you get a chance to talk to Alex Bishop, don't be too harsh on D to him, I'm trying to convince him to make the switch :)

With the input from ponce (*) I now have the code working. Now all is need is a time machine so as to redo the demo successfully. Doctor, where are you? Oh you are committed to be on BBC1 in two hours time.

Get Alex to have a chat with me and I can show the demonstration working.


(*) ponce is arguably not the most positive or constructive name to go
by.
-- 
Russel. ============================================================================= Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder@ekiga.net 41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel@winder.org.uk London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

On Saturday, 19 September 2015 at 16:15:45 UTC, Russel Winder wrote:
> Sadly the:
>
>  pragma(LDC_global_crt_ctor, 0)
>     void initRuntime() {
>       import core.runtime: Runtime;
>       Runtime.initialize();
>    }
>
> will not compile under DMD :-(

version(LDC){ /* ... */ }

not that it helps make things work correctly, but at least they'll compile :)