GNU bug report logs - #35666
[PATCH 0/2] Build a thread-safe hdf5 library

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Message #37 received at 35666 <at> debbugs.gnu.org (full text, mbox):

From: Eric Bavier <bavier <at> cray.com>
To: Ludovic Courtès <ludovic.courtes <at> inria.fr>
Cc: Ricardo Wurmus <rekado <at> elephly.net>,
 "35666 <at> debbugs.gnu.org" <35666 <at> debbugs.gnu.org>,
 "pgarlick <at> tourbillion-technology.com" <pgarlick <at> tourbillion-technology.com>
Subject: Re: [bug#35666] [PATCH 0/2] Build a thread-safe hdf5 library
Date: Tue, 14 May 2019 14:40:35 +0000

> I’m not sure I understand.  Do you mean that, just because you use the
> C++ API instead of the C API, the library is not thread-safe?

The thread-safety of the C++ interface itself is not guaranteed/"supported".

> They do see crashes vanish when using the library compiled with
> ‘--enable-threadsafe’, and reliably so.

Great.  I'm not familiar enough with the C++ interface code to say which areas might cause problems in a threaded context.  It's likely that whatever problems they were seeing before was not at the interface layer but deeper.

Eric Bavier, Scientific Libraries, Cray Inc.

________________________________________
From: Ludovic Courtès <ludovic.courtes <at> inria.fr>
Sent: Tuesday, May 14, 2019 02:28
To: Eric Bavier
Cc: Ricardo Wurmus; 35666 <at> debbugs.gnu.org; pgarlick <at> tourbillion-technology.com
Subject: Re: [bug#35666] [PATCH 0/2] Build a thread-safe hdf5 library

Hi Eric,

Eric Bavier <bavier <at> cray.com> skribis:

> I think this should be fine, though I've not heard of anyone who has
> relied on this feature.  The "unsupported" part here is that the posix
> lock used for thread-safety is not hoisted into the higher-level API
> calls.  So if your colleague is using the C++ interface and expecting
> thread-safety, they are out of luck.  So the disclaimer is that only
> the low-level C interface gains thread-safety, and the rest are no
> better.

I’m not sure I understand.  Do you mean that, just because you use the
C++ API instead of the C API, the library is not thread-safe?

They do see crashes vanish when using the library compiled with
‘--enable-threadsafe’, and reliably so.

Thanks,
Ludo’.

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