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October 18, 2012
independent or parallel process
I want the function below to run independently -- like a unix
background process, without delaying subsequent code in main.  I
tried the following using std.parallelism:

void main() {
   function_a(int a, int b) {
    ...
   }

   auto new_task = task!function_a(11, 12);
   new_task.executeInNewThread(1);

   // more code ...
}


I get errors: core.thread.ThreadException ... unable to set
thread priority ...
October 18, 2012
Re: independent or parallel process
On 10/17/2012 07:46 PM, drpepper wrote:
> I want the function below to run independently -- like a unix
> background process, without delaying subsequent code in main. I
> tried the following using std.parallelism:
>
> void main() {
> function_a(int a, int b) {
> ...
> }
>
> auto new_task = task!function_a(11, 12);
> new_task.executeInNewThread(1);
>
> // more code ...
> }
>
>
> I get errors: core.thread.ThreadException ... unable to set
> thread priority ...

I am not sure whether it is supposed to be, but the function must be a 
module-level function; so define it outside of main.

When I did that, there was segmentation fault if I used thread priority.

Workaround:

1) Take function out of main

2) Do not specify thread priority

Created bug report:

  http://d.puremagic.com/issues/show_bug.cgi?id=8849

Ali
October 19, 2012
Re: independent or parallel process
Thank you Ali,

Indeed, I originally had the function outside of main.

I have found another strange result with std.concurrency:

spawn(&function, array[0].length, array.length);
// generates compiling error: "cannot deduce template function
from arg types"

//Yet,
int var_one = array[0].length;
int var_two = array.length;
spawn(&function, var_one, var_two);
// compiles and runs



On Thursday, 18 October 2012 at 17:52:09 UTC, Ali Çehreli wrote:
> On 10/17/2012 07:46 PM, drpepper wrote:
>> I want the function below to run independently -- like a unix
>> background process, without delaying subsequent code in main. I
>> tried the following using std.parallelism:
>>
>> void main() {
>> function_a(int a, int b) {
>> ...
>> }
>>
>> auto new_task = task!function_a(11, 12);
>> new_task.executeInNewThread(1);
>>
>> // more code ...
>> }
>>
>>
>> I get errors: core.thread.ThreadException ... unable to set
>> thread priority ...
>
> I am not sure whether it is supposed to be, but the function 
> must be a module-level function; so define it outside of main.
>
> When I did that, there was segmentation fault if I used thread 
> priority.
>
> Workaround:
>
> 1) Take function out of main
>
> 2) Do not specify thread priority
>
> Created bug report:
>
>   http://d.puremagic.com/issues/show_bug.cgi?id=8849
>
> Ali
October 19, 2012
Re: independent or parallel process
On 10/18/2012 06:34 PM, drpepper wrote:
> Thank you Ali,
>
> Indeed, I originally had the function outside of main.
>
> I have found another strange result with std.concurrency:
>
> spawn(&function, array[0].length, array.length);
> // generates compiling error: "cannot deduce template function
> from arg types"
>
> //Yet,
> int var_one = array[0].length;
> int var_two = array.length;
> spawn(&function, var_one, var_two);
> // compiles and runs

Reduced code:

void bar(T...)(void function(T) fn, T args)
{}

void foo(size_t i)
{}

void main() {
    bar(&foo, 42);    // <-- compilation error
}

std.concurrency.spawn has the same signature as bar. The problem is with 
that signature: It requires that the arguments must match the parameters 
of the function.

Changing the signature of spawn() to the signature of the following 
bar() should work:

void bar(Func, T...)(Func fn, T args)
    if (__traits(compiles, fn(args)))
{}

void foo(size_t i)
{}

void main() {
    bar(&foo, int.init);      // <-- now compiles
    bar(&foo, size_t.init);
}

I wonder whether others see any weakness in that signature. If not, it 
can be entered to bugzilla as an enhancement request.

Ali
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