• John Burak <icrashedtheinternet gmail.com> Aug 06 2007
• Sean Kelly <sean f4.ca> Aug 06 2007
• Regan Heath <regan netmail.co.nz> Aug 07 2007
• =?ISO-8859-1?Q?Julio_C=E9sar_Carrascal_Urquijo?= Aug 07 2007
• Robert Fraser <fraserofthenight gmail.com> Aug 06 2007

I am looking into D as a possibility for a programming project I want to start.
 Can someone point me to resources on how D supports parallel programming,
assuming it does?  I'm surprised I didn't notice anything about parallel
programming on the "d language overview" page when I scanned/searched it. 
Unless it is there and I missed it (quite possible) then I think it should be
added so people know what D is capable of (I'm still assuming it has some
native support for parallel programming).

-John

John Burak wrote:
 I am looking into D as a possibility for a programming project I want to
start.  Can someone point me to resources on how D supports parallel
programming, assuming it does?  I'm surprised I didn't notice anything about
parallel programming on the "d language overview" page when I scanned/searched
it.  Unless it is there and I missed it (quite possible) then I think it should
be added so people know what D is capable of (I'm still assuming it has some
native support for parallel programming).


Support for multithreaded programming (what I assume you meant by 
"parallel programming") in D largely amounts to a standard Thread object 
in the library, as well as a "synchronized" keyword which behaves quite 
similar to the one in Java.  There is also a "volatile" keyword, but it 
is really only intended for lock-free programming and thus doesn't see 
much use outside of library code.

If it helps, Tango also contains a Fiber implementation, a read-write 
mutex, condition variables, and semaphores.  There is also a coroutine 
implementation and a CSP implementation at http://www.assertfalse.com.

I think we still have a ways to go for easily usable concurrency in D, 
but the basic building blocks are there.


Sean

Sean Kelly wrote:
 Support for multithreaded programming (what I assume you meant by 
 "parallel programming") in D largely amounts to a standard Thread object 
 in the library, as well as a "synchronized" keyword which behaves quite 
 similar to the one in Java.  


Except that (importantly, IMO) it's re-entrant.
By that I mean, if you have:

class Foo
{
   int i;

   void bar()
   {
     synchronized(this)
     {
       i++;
     }
   }
}

void main()
{
   Foo f = new Foo();
   synchronized(f)
   {
     f.bar();
   }
}

you get no deadlock.  As I believe they do in Java (someone correct me 
if I'm wrong).

In short, multiple synchronized blocks, on the same object, in the same 
thread are allowed and do not cause a deadlock.

Anyone know what the C# behaviour is in this case?

Regan

Regan Heath wrote:
 Anyone know what the C# behaviour is in this case?


using System;

class Foo
{
	int i;
	public void bar()
	{
		lock (this)
		{
			i++;
		}
	}

	public static void Main()
	{
		Foo f = new Foo();
		lock (f)
		{
			f.bar();
		}
	}
}

It works but it is always recommended to lock on a private object 
because there are some corner cases where it will dead-lock. Something 
like the following is always preferred:

	readonly object syncRoot = new object();

	(...)
	lock (syncRoot)
	{
		(...)
	}

John Burak Wrote:

 I am looking into D as a possibility for a programming project I want to
start.  Can someone point me to resources on how D supports parallel
programming, assuming it does?  I'm surprised I didn't notice anything about
parallel programming on the "d language overview" page when I scanned/searched
it.  Unless it is there and I missed it (quite possible) then I think it should
be added so people know what D is capable of (I'm still assuming it has some
native support for parallel programming).
 
 -John


It has a synchronized keyword and threads in both standard libraries (Tango's
threading support is a bit more robust, as it has futures and fibers)...