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Newsgroups: comp.lang.ada
Subject: Re: Is the Ada run-time required to detect out-of-memory
 conditions?
References: <878yfmiuak.fsf@insalien.org> <2h7b84Fa2aefU1@uni-berlin.de>
From: Ludovic Brenta <ludovic.brenta@insalien.org>
Date: Sat, 22 May 2004 00:04:40 +0200
Message-ID: <87n041l9mv.fsf@insalien.org>
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Date: 2004-05-22T00:03:34+02:00
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> Hi,
>
> I'm the original reporter of the bug. I forgot to mention that I
> limited the virtual memory of the process using 'ulimit -v 100000'
> in a bash.
>
> I'm very new to Ada, but I'm impressed of all the features. In
> parallel I'm developing a little library to make C programming
> easier. In this library I malloc'ed some "emergency memory" at the
> program start which is simply freed when the process gets out of
> memory. Then the error handler can at least raise an exception or
> print some warning.
>
> Perhaps the GNAT runtime library could use a similar approach.

I just closed your bug report after determining that the issue was not
in libgnat but in the kernel.  Basically, Linux sends SIGKILL to
programs that exhaust physical RAM; as you know, SIGKILL cannot be
caught so libgnat has no chance to raise an exception.  If the virtual
memory is exhausted before physical memory is, then libgnat does raise
Storage_Error.

I am quite confident that you can implement your "emergency memory"
scheme in Ada, but this will not do anything to prevent SIGKILL.  At
best, you can recover from a SIGSEGV.  This is true also of your C
library.

BTW, why not view the Ada compiler and library as "a library to make C
programming easier"? :)

-- 
Ludovic Brenta.