From: Anders Fugmann <anders@fugmann.net>
To: ygrek <ygrek@autistici.org>
Cc: caml-list <caml-list@inria.fr>
Subject: Re: [Caml-list] Bug when printing from signal handlers?
Date: Thu, 20 Mar 2014 08:42:47 +0100 [thread overview]
Message-ID: <532A9BF7.6050705@fugmann.net> (raw)
In-Reply-To: <20140320132941.09aa04f4@kiwi.local.tld>
On 03/20/2014 06:29 AM, ygrek wrote:
>
> stdlib channels are protected with non-recursive mutex, so the deadlock on re-entrant invocation is guaranteed.
I also assumed when I first saw the behavior that it was some deadlock.
But it seems that that is not the case as the system enters a live lock
and just sits there burning off cpu time.
> AFAICS runtime system tries to execute signal immediately (see signal_handle in asmrun/signals_asm.c)
> and if that is not possible - records signal for later execution.
> Anyway doing complex stuff in signal handler is a bad idea, because even with delayed processing (when
> things are safe from the libc point of view) the points of invocation of OCaml signal handler are scattered
> all around the program (allocation sites) and any OCaml resource that doesn't support reentrant usage will break
> the program.
Maybe the documentation should be updated to explain how signal handling
works and what is allowed in signal handers. Possibly also ideas on how
to cope with these limitations.
I circumvented the problem by using unbuffered writes (Unix.write), but
it makes me wonder if I have code erroneous code lying around.
/Anders
next prev parent reply other threads:[~2014-03-20 7:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-19 21:21 Anders Peter Fugmann
2014-03-19 22:19 ` Jesper Louis Andersen
2014-03-19 23:21 ` Gerd Stolpmann
2014-03-20 5:29 ` ygrek
2014-03-20 7:42 ` Anders Fugmann [this message]
2014-03-20 20:07 ` Gerd Stolpmann
2014-03-23 10:01 ` ygrek
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