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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Finalization of library level tasks
Date: Thu, 19 Apr 2018 08:34:47 +0100
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Date: 2018-04-19T08:34:47+01:00
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AdaMagica <christ-usch.grein@t-online.de> writes:

> Am Mittwoch, 18. April 2018 16:52:04 UTC+2 schrieb J-P. Rosen:

>> OK. You were actually quite close... Use a killer task (with the same
>> master as your worker) like this:
>> 
>> task Killer is
>>    entry Never_Called;
>> end Killer;
>> 
>> task body Killer is
>> begin
>>    accept Never_Called;
>> exception
>>    when Tasking_Error =>
>>      -- Kill the other task
>> end Killer;
>> 
>> Hint: when the master completes, Tasking_Error is raised in all tasks
>> waiting on entries that depend on that master.
>
> I do not understand how this is supposed to work.

I tried this:

   with Killer_Pack;
   procedure Killing is
   begin
      null;
   end Killing;
   
   package Killer_Pack is
      task Killer is
         entry Never_Called;
      end Killer;
   end Killer_Pack;

   with GNAT.IO;
   package body Killer_Pack is
      task body Killer is
      begin
         accept Never_Called;
      exception
         when Tasking_Error =>
            GNAT.IO.Put_Line ("bye.");
      end Killer;
   end Killer_Pack;

with all the GNATs I could lay my hands on (macOS) and they all hang:
under gdb,

   (gdb) info tasks
      ID       TID P-ID Pri State                  Name
   *   1 101000000       31 Child Termination Wait main_task
       2 101000e00    1  31 Accept or Select Term  killer

Of course, I'm quite prepared to believe I've misunderstood the point.