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Re: How to kill slave kernel securely?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg117176] Re: How to kill slave kernel securely?
  • From: John Fultz <jfultz at wolfram.com>
  • Date: Thu, 10 Mar 2011 16:02:23 -0500 (EST)

That's just not how modern operating systems work.  All memory is virtual 
memory.  Whether it's backed by RAM, disk, or some other storage medium is a 
detail that the operating system manages, not applications (with the exception 
of mechanisms like memory-mapped files).  And if an application did have the 
ability to lock its memory into RAM, it would be quite unfriendly indeed to 
other applications on the system.

Would you really want an app that insisted on keeping 2 gigabytes of RAM in play 
for itself (or ten applications that could keep 200 megabytes each), even if the 
application didn't happen to be doing any computation right now and other apps 
were totally starved for RAM?  This could lead to a total failure of the 
operating system itself, which is much worse than swapping.

Modern operating systems simply cannot allow apps to behave in that fashion.  If 
they did, then instead of swap hell, you would end up with routine failures of 
the entire operating system itself.

Sincerely,

John Fultz
jfultz at wolfram.com
User Interface Group
Wolfram Research, Inc.



On Thu, 10 Mar 2011 06:12:04 -0500 (EST), Alexey Popkov wrote:
> Instead of MemoryConstrained I would prefer to have
> 'FreeMemoryConstrained'
> function to protect from swapping securely...
>
>
> ----- Original Message -----
> From: "Oliver Ruebenkoenig" <ruebenko at wolfram.com>
> To: "Alexey Popkov" <lehin.p at gmail.com>
> Cc: "comp.soft-sys.math.mathematica" <mathgroup at smc.vnet.net>
> Sent: Wednesday, March 09, 2011 9:46 PM
> Subject: [mg117134] Re: [mg117082] How to kill slave kernel securely?
>
>
>> On Wed, 9 Mar 2011, Alexey Popkov wrote:
>>
>>> Oliver,
>>>
>>> Is this a good way to do when the slave kernel freezes because of
> swapping?
>
>>> Alexey
>>>
>>>
>> Alexey,
>>
>> You could try MemoryConstrained and use Quit for the failexpr.
>>
>> Oliver
>>
>>>
>>> ----- Original Message -----
>>> From: "Oliver Ruebenkoenig" <ruebenko at wolfram.com>
>>> Newsgroups: wri.mathgroup
>>> To: "Alexey" <lehin.p at gmail.com>
>>> Cc: <mathgroup at smc.vnet.net>
>>> Sent: Wednesday, March 09, 2011 5:11 PM
>>> Subject: Re: [mg117082] How to kill slave kernel securely?
>>>
>>>
>>>> On Wed, 9 Mar 2011, Alexey wrote:
>>>>
>>>>> Good day,
>>>>>
>>>>> LinkClose[link] "does not necessarily terminate the program at the
>>>>> other end of the connection" as it is said in the Documentation.
>>>>> Is
>>>>> there a way to kill the process of the slave kernel securely?
>>>>>
>>>>>
>>>> Alexey,
>>>>
>>>> you could use Quit.
>>>>
>>>> Oliver




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