Re: Ruby/YARV thread question

Hi,

Michael Neumann wrote:
> In thread.c, three YARV thread models are described. Which models will be
> used in Ruby/YARV? If model 2 (native threads with Giant VM lock) is used,
> can I use blocking system calls without releasing the Giant VM lock before?
> Probably not. I'm trying to understand how the future Ruby will behave in
> this respect.

Yes.  You must release Giant VM Lock before doing blocking task.  If you
need do this in extension libraries, use rb_thread_blocking_region() API.


API:
rb_thread_blocking_region(
  blocking_func, /* function that that will block */
  data,          /* this will be passed above function */
  unblock_func   /* if another thread cause exception with Thread#raise,
                    this function is called to unblock or NULL */
)

usage:

/* this function block some mins
 */
VALUE
solve_difficult_numerical_problem(void *p) {
  /* this needs some mins */
  return result;
}

/* unblock function
 */
void
ubf_solve_difficult_numerical_problem(rb_thread_t *)
{
  /* set flag it specify interrupts */
}

/* rb_define_method(klass, solve_difficult_numerical_problem_method, 1);
 */
VALUE
solve_difficult_numerical_problem_method(VALUE arg)
{
  void *data = /* ... */;
  return rb_thread_blocking_region(
           solve_difficult_numerical_problem,
           data,
           ubf_solve_difficult_numerical_problem);
}

notice:
(1) If you run on Parallel computer like multi-core CPU, you can run
above solve_difficult_numerical_problem() in *parallel*.  Of course, you
must make this function thread safe.

(2) You can't call Ruby's method from
solve_difficult_numerical_problem().  I'll prepare API to support this.

(3) some system calls like pthread_mutex_lock() has no way to unblock.
this means that you can't interrupt these system calls and can't
interrupt with timeout().

(3') select() system call can be interrupted with pthread_kill().  But
on cygwin system, pthread_kill() doesn't work well.  oops.


Regards,
-- 
// SASADA Koichi at atdot dot net