From: Bardur Arantsson <spam@scientician.net>
To: caml-list@inria.fr
Subject: Re: Unix.localtime not threadsafe?
Date: Sat, 03 Sep 2005 09:03:08 +0200 [thread overview]
Message-ID: <dfbhrc$e28$1@sea.gmane.org> (raw)
In-Reply-To: <891bd339050902103460db1a55@mail.gmail.com>
Yaron Minsky wrote:
> I was looking at the Unix.localtime implementation, and it appears to
> me that it's not threadsafe. I'm wondering if anyone can confirm.
>
> First off, the underlying localtime call is definitely not re-entrant.
> The tm data structure is shared among all calls, leading to the
> possibility of races. What I'm not sure of is whether there can be a
> race given the locking of the OCaml runtime. Here's the code from
> gmtime.c in the ocaml distribution:
I don't think the glibc/Linux localtime() man page explicitly states
this, but I expect that it returns a pointer to a *thread-local*
statically allocated struct tm... in which case there's no problem.
Most other system functions whose API looks non-threadsafe do the same.
('errno' would be the standard example).
[--snip--]
--
Bardur Arantsson
<bardur@imada.sdu.dk>
<bardur@scientician.net>
- But don't be reading my mind between 4 and 5. That's Willie's
time!
Groundskeeper Willie, 'The Simpsons'
next prev parent reply other threads:[~2005-09-03 7:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-02 17:34 Yaron Minsky
2005-09-03 7:03 ` Bardur Arantsson [this message]
2005-09-03 7:20 ` [Caml-list] " Florian Weimer
2005-09-03 7:54 ` [Caml-list] " Xavier Leroy
2005-09-03 11:14 ` Yaron Minsky
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