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[Python-ideas] Memory limits [was Re: Membership of infinite iterators]

Giampaolo Rodola' g.rodola at gmail.com
Thu Oct 19 16:52:42 EDT 2017 
On Thu, Oct 19, 2017 at 10:05 AM, Stephan Houben <stephanh42 at gmail.com>
wrote:

> Hi Steve,
>
> 2017-10-19 1:59 GMT+02:00 Steven D'Aprano <steve at pearwood.info>:
>
>> On Wed, Oct 18, 2017 at 02:51:37PM +0200, Stefan Krah wrote:
>>
>> > $ softlimit -m 1000000000 python3
>> [...]
>> > MemoryError
>> >
>> >
>> > People who are worried could make a python3 alias or use Ctrl-\.
>>
>> I just tried that on two different Linux computers I have, and neither
>> have softlimit.
>>
>>
> Yeah, not sure what "softlimit" is either.
> I'd suggest sticking to POSIX-standard ulimit or just stick
> something like this in the .pythonrc.py:
>
> import resource
> resource.setrlimit(resource.RLIMIT_DATA, (2 * 1024**3, 2 * 1024**3))
>
> Nor (presumably) would this help Windows users.
>>
>
> I (quickly) tried to get something to work using the win32 package,
> in particular the win32job functions.
> However, it seems setting
> "ProcessMemoryLimit" using win32job.SetInformationJobObject
> had no effect
> (i.e.  a subsequent win32job.QueryInformationJobObject
> still showed the limit as 0)?
>
> People with stronger Windows-fu may be aware what is going on here...
>
> Stephan
>

I wasn't aware Windows was capable of setting such limits in a per-process
fashion. You gave me a good idea for psutil:
https://github.com/giampaolo/psutil/issues/1149
According to this cmdline tool:
https://cr.yp.to/daemontools/softlimit.html
....the limit should kick in only when the system memory is full, whatever
that means:
<<-r n: Limit the resident set size to n bytes. This limit is not enforced
unless physical memory is full.>>
...so that would explain why it had no effect.

-- 
Giampaolo - http://grodola.blogspot.com
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