Re: Is the Ada run-time required to detect out-of-memory conditions?

[Mark H Johnson <mark_h_johnson@raytheon.com>]

Ludovic Brenta wrote:
> Hello,
> 
> I have received a bug report [1] against GNAT 3.15p and reproduced the
> same behaviour with GCC 3.4.  [snip]
> My first impression is that the program exhausts physical memory (RAM
> + swap) before exhausting the default storage pool, the size of which
> is defined to be the total size of the virtual address space.  As a
> result, the kernel detects the out-of-memory condition before the Ada
> run-time library does, and sends SIGKILL to the program.  Of course,
> the program has no chance to turn SIGKILL into an exception.
> 
> Is my assessment correct?  Is this a bug in the GNAT library?
Well - if the OOM killer is getting rid of the application, you should 
be able to do something like the following...
  - allocate a bunch of storage with program A and then wait
  - run another copy of A and then wait
repeat running new copies until someone gets killed. If its the OOM 
killer and it kills any but the last copy - it cannot be a GNAT library 
problem. You HAD enough storage when you went into the wait but globally 
don't now. I don't see how any run time could prevent such a situation 
(especially since the program that "broke the camel's back" could be 
implemented in any language).

Also - have you checked the console / system logs for any indication 
that the OOM killer is at work?
   --Mark