Asynchronous abort not working in Debian GNAT?

Asynchronous abort not working in Debian GNAT?

[Niklas Holsti]

Under Debian Sarge on Intel, gnat 3.15p, I implemented a time-out for an 
application using the canonical construct:

     select
        delay Time_Out;
        Error (...);
     then abort
        Processing (...);
     end select;

After upgrading to Debian Lenny, FSF GNAT 4.3.2, it appears that this no 
longer works; instead, Processing completes without being aborted, 
unless Processing does something that probably invokes scheduling, for 
example "delay 0.0" or Text_IO output to the console.

Running "strace" on the program shows that a SIGABRT is signalled at 
TIme_Out, but does not abort Processing until Processing does something 
like delay or console output. The GNAT polling option (-gnatP) does not 
seem to help.

I did not find any Debian bug report on this issue. Has anyone else seen 
this? Do you know of work-arounds? Other than sprinkling the code with 
frequent delay statements.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .

Re: Asynchronous abort not working in Debian GNAT?

[Georg Bauhaus]

Niklas Holsti wrote:
> Under Debian Sarge on Intel, gnat 3.15p, I implemented a time-out for an
> application using the canonical construct:
> 
>     select
>        delay Time_Out;
>        Error (...);
>     then abort
>        Processing (...);
>     end select;
> 
> After upgrading to Debian Lenny, FSF GNAT 4.3.2, it appears that this no
> longer works; instead, Processing completes without being aborted,
> unless Processing does something that probably invokes scheduling, for
> example "delay 0.0" or Text_IO output to the console.

FWIW, with Windows GNAT GPL 2007 (gcc 4.1.3), it doesn't abort either,

with Ada.Text_IO;

procedure Time_Out is

   procedure Processing is
      type T is mod 2**16;
      X: T;
   begin
      Very_Busy: loop
         X := T'Succ(X);
      end loop Very_Busy;
   end Processing;

   procedure Error(Message: String) is
      use Ada;
   begin
      Text_IO.Put_Line(Text_Io.Current_Error,
        MEssage);
   end Error;

begin
   select
      delay 10.0;
      Error("over");
   then abort
      Processing;
   end select;
end Time_Out;