Re: dynamic vs static tasks allocation

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 10/16/2014 10:25 AM, Stribor40 wrote:
> If you know ahead of time how many tasks will be needed is it better to
> create tasks dynamically with new operator or just statically?
> 
> Which is way is recommended and why even bother allocating dynamically?

There are actually 3 ways to create tasks:

1. Statically, in a pkg or the main procedure:

package body P is
   task Foo is

2. Dynamically without access types, using block statements or subprograms:

task type Foo;

type Foo_List is array (Positive range <>) of Foo;

procedure P (Num_Workers : in Positive) is
   Worker : Foo_List (1 .. N);

3. Dynamically with access types, using new:

task type Foo;
type Foo_Ptr is access Foo;

Worker : Foo_Ptr;
...
Worker := new Foo;

1 and 2 are often both considered static allocation.

The trouble with 3, as with any use of access types, is memory management. With
access-to-task types, you also have to be sure the task has terminated before
freeing it. For these reasons, I avoid 3 whenever possible.

-- 
Jeff Carter
"I blow my nose on you."
Monty Python & the Holy Grail
03