Strange exception using threads

[simendsjo]

On Sat, 23 Jun 2012 18:05:47 +0200, Minas Mina  
<minas_mina1990 at hotmail.co.uk> wrote:

> I am using a secondary thread to send messages to it so it can print  
> those messages.
>
> import std.stdio;
> import std.concurrency;
>
> void main()
> {
> 	auto low = 0, high = 10;
> 	
> 	auto tid = spawn(&writer);
> 	
> 	foreach(i; low..high)
> 	{
> 		writeln("Main thread: ", i);
> 		tid.send(tid, i);
> 	}
> }
>
> void writer()
> {
> 	while( true )
> 	{
> 		receive(
> 			(Tid id, int i)
> 			{
> 				writeln("Secondary thread: ", i);
> 			}
> 		);
> 	}
> }
>
> This is the result:
> Main thread: 0
> Main thread: 1
> Main thread: 2
> Main thread: 3
> Main thread: 4
> Main thread: 5
> Main thread: 6
> Main thread: 7
> Main thread: 8
> Main thread: 9
> Secondary thread: 0
> Secondary thread: 1
> Secondary thread: 2
> Secondary thread: 3
> Secondary thread: 4
> Secondary thread: 5
> Secondary thread: 6
> Secondary thread: 7
> Secondary thread: 8
> Secondary thread: 9
> std.concurrency.OwnerTerminated at std/concurrency.d(248): Owner terminated
> ----------------
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool  
> std.concurrency.MessageBox.get!(void function(std.concurrency.Tid,  
> int)*).get(scope void function(std.concurrency.Tid, int)*).bool  
> onControlMsg(ref std.concurrency.Message)+0x2a) [0x437016]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool  
> std.concurrency.MessageBox.get!(void function(std.concurrency.Tid,  
> int)*).get(scope void function(std.concurrency.Tid, int)*).bool scan(ref  
> std.concurrency.List!(std.concurrency.Message).List)+0x68) [0x437084]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(bool  
> std.concurrency.MessageBox.get!(void function(std.concurrency.Tid,  
> int)*).get(scope void function(std.concurrency.Tid, int)*)+0x88)  
> [0x436c20]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void  
> std.concurrency.receive!(void function(std.concurrency.Tid,  
> int)*).receive(void function(std.concurrency.Tid, int)*)+0x32) [0x436b86]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void  
> main.writer()+0x13) [0x43066b]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(_D3std11concurrency11__T6_spawnZ6_spawnFbPFZvZS3std11concurrency3Tid4execMFZv+0x45)  
> [0x430941]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(void  
> core.thread.Thread.run()+0x2a) [0x4470fe]
> /home/minas/Projects/D/D_Test/D_Test/bin/Debug/D_Test(thread_entryPoint+0xf3)  
> [0x446e97]
>
> The program runs correctly but then boom! Does anyone know why?

You can notify child threads that their owner terminates so they can  
finish up

import std.stdio;
import std.concurrency;

void main()
{
	auto low = 0, high = 10;
	
	auto tid = spawnLinked(&writer);
	
	foreach(i; low..high)
	{
		writeln("Main thread: ", i);
		tid.send(tid, i);
	}
     writeln("need to gracefully terminate child threads");
     tid.send(tid, Term());
     writeln("term sent");
}

struct Term {}
void writer()
{
     bool done;
	while( !done )
	{
		receive(
			(Tid id, int i)
			{
				writeln("Secondary thread: ", i);
			},
             (Tid id, Term term)
             {
                 writeln("Owner terminated, so do we");
                 done = true;
             }
		);
	}
}


Main thread: 0
Main thread: 1
Main thread: 2
Main thread: 3
Main thread: 4
Secondary thread: 0
Secondary thread: 1
Secondary thread: 2
Secondary thread: 3
Secondary thread: 4
Main thread: 5
Main thread: 6
Main thread: 7
Main thread: 8
Main thread: 9
Secondary thread: 5
Secondary thread: 6
need to gracefully terminate child threads
term sent
Secondary thread: 7
Secondary thread: 8
Secondary thread: 9
Owner terminated, so do we