Hi,
Interesting "feature" in 10.11.4. I wonder if the process is killed
before or after malloc() returns. If before, it seems very blunt:
"You're asking too much and I don't like it so I kill you now".
If after it doesn't look much better: "You're asking a lot and I
don't like it but I give it to you anyway. I'll kill you quickly
later".
Why wouldn't the kernel just refuse to give that memory instead
(i.e. malloc() returns NULL).
Just curious...
H.
On 05/04/2016 06:21 PM, Simon Urbanek wrote:
On May 4, 2016, at 9:00 PM, Marius Hofert <marius.hof...@uwaterloo.ca> wrote:
Hi Simon,
thanks for your quick reply.
1) ... so you can reproduce this?
Yes, I can on 10.11.4.
2) Do you know a way how this can be 'foreseen'? We allocate larger
matrices in the copula package depending on the user's input
dimension. It would be good to tell her/him "Your dimension is quite
large. Be aware of killers in your neighborhood"... before the killer
attacks.
Not directly, because the system is happy to accommodate R's request for more
memory but then it will strike out of the blue. Since that decision is made by
the kernel and it doesn't expose its thinking about how it feels, it's hard to
tell. I couldn't find any API on OS X akin to didReceiveMemoryWarning in iOS,
unfortunately.
You could guess - e.g. by checking the total system memory
int mib [] = { CTL_HW, HW_MEMSIZE };
int64_t value = 0;
size_t length = sizeof(value);
sysctl(mib, 2, &value, &length, NULL, 0);
and comparing it to the sizes involved. However, even that is not foolproof,
because it all depends on the other processes' memory usage, swap space size
etc. There are slightly more involved ways to query the VM system as well, but
I'm not sure I'd want to go so deep into the weeds, especially since this
becomes quickly highly OS-specific.
Cheers,
Simon
Thanks & cheers,
Marius
On Wed, May 4, 2016 at 8:54 PM, Simon Urbanek
<simon.urba...@r-project.org> wrote:
On May 4, 2016, at 6:14 PM, Marius Hofert <marius.hof...@uwaterloo.ca> wrote:
Can you elaborate on "leads to R being killed"? You should tell to the killer
not to do it again :).
Hi Simon!
Sure, but who do you tell it if you don't know the killer?
This is all the killer left me with, the 'crime scene' if you like :-)
m <- matrix(0, 90000, 100000)
Killed: 9
My colleague Wayne Oldford also tried it on his Mac machine and
apparently the killer went further down the hallway to his office
now... so scary. Here is Wayne's sessionInfo():
Yes, indeed, scary - since it means someone is killing R which means there is
not much R itself can do about it. In fact from the syslog I see
May 4 20:48:11 ginaz kernel[0]: low swap: killing pid 56256 (R)
so it's the kernel's own defense mechanism. The bad thing is that R cannot do
anything about it - the kernel just decides to snipe processes it thinks are
dangerous to the health of the system, and it does so without a warning.
Cheers,
Simon
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Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
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