Re: [starpu-devel] StarPU Question: Using Local Variable as Data Handles?

[Samuel Thibault <samuel.thibault@inria.fr>]

Hello,

Xinbo Li, le jeu. 17 avril 2025 21:20:56 +0000, a ecrit:
> Is it safe to define a starpu_data_handle_t as a local variable for the 
> purpose
> of task submission?
[...]
> My concern is whether StarPU may run into undefined behavior or errors
> when the scheduled task is executed, since it may no longer be able to
> access the handle:

starpu_data_handle_t is just a pointer, so losing it is "safe", sure,
but you need to deallocate it first :)

> For example, in the code snippet below, the handle is
> declared within a local scope. Once the block ends, the variable handle is 
> no
> longer accessible.

So you need to unregister it. Either waiting for tasks with
starpu_data_unregister or without waiting for tasks with
starpu_data_unregister_submit.

Samuel

> DataType data;
> 
> {
>     preparation(&data);
> 
>     starpu_data_handle_t handle;
>     starpu_custom_data_register(&handle, STARPU_MAIN_RAM, &data);
> 
>     starpu_task_insert(
>         &some_codelet,
>         STARPU_RW, handle,
>         0);
> }