From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: *
X-Spam-Status: No, score=1.3 required=5.0 tests=BAYES_00,INVALID_MSGID,
	MSGID_RANDY autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,790d824907970cc3
X-Google-Attributes: gid103376,public
From: dennison@telepath.com
Subject: Re: Exception Propagation
Date: 1999/06/14
Message-ID: <7k393k$sb5$1@nnrp1.deja.com>#1/1
X-Deja-AN: 489464321
References: <7jjbl4$n79$1@nnrp1.deja.com> <b3T63.5112$y6.2934699@WReNphoon3>
 <7jh857$ej$1@nnrp1.deja.com> <375CC549.7EDFB885@spam.com>
 <0nc73.5376$y6.3195132@WReNphoon3> <7jlud1$l76$1@nnrp1.deja.com>
 <wccd7yyrgfu.fsf@world.std.com>
X-Http-Proxy: 1.0 x35.deja.com:80 (Squid/1.1.22) for client 204.48.27.130
Organization: Deja.com - Share what you know. Learn what you don't.
X-Article-Creation-Date: Mon Jun 14 16:03:08 1999 GMT
Newsgroups: comp.lang.ada
X-Http-User-Agent: Mozilla/4.6 [en] (WinNT; I)
Date: 1999-06-14T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <wccd7yyrgfu.fsf@world.std.com>,
  Robert A Duff <bobduff@world.std.com> wrote:
> dennison@telepath.com writes:
>

> > If you *do* write such code in last-ditch handlers on your tasks,
make
> > sure to handle the IO synchronization problem yourself, or you are
> > liable to get interspersed output, or different exceptions than the
ones
> > you are looking for.
>
> Hmm.  Maybe.  But the more complicated you make that
exception-handling
> code, the more likely that *it* will have the same problem -- and
whose
> going to handle exceptions in the exception handler?

In my experience if you try to use an unprotected Text_IO in last-ditch
exception handlers in a multitask program, you are almost *guaranteed*
to get an exception in your exception handlers. When one task dies, any
task attempting to rendezvous with it will die too. Tasks looking to
rendezvous with those newly dead tasks will then die. Thus task
terminations tend to spread through the system like a cold through a
daycare center. The odds of more than one task trying to simultaniously
do text I/O from its exception handler gets to be awfully close to 1.0

--
T.E.D.


Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.