Re: Stack size limits
Re: Stack size limits
- Subject: Re: Stack size limits
- From: Volker Blum <email@hidden>
- Date: Tue, 11 Jul 2017 23:49:12 +0200
Thanks!
True, the hard limit in these xterms is also 512. It does sound like the limit
for threads, not for processes.
Trouble is that this is a new installation of both MacOS and XQuartz. On my
past system, my xterms had the usual 65532 hard limits.
Did anyone try this in MacOS 10.12.5 ? Could it be that something in the
windows opened by the OS on behalf of X11 changed in this OS release?
[I am also not sure which configuration script(s) for X11 might even be
relevant … I think I never touched any of these, since the early 2000’s on
Linux … hm.]
Best
Volker
> On Jul 11, 2017, at 7:18 PM, Mike Thornburg <email@hidden> wrote:
>
> On Tue, 11 Jul 2017, Tom Lane wrote:
>
>> "David Ledger" <email@hidden> writes:
>>> On 11 Jul 2017, at 14:18, Volker Blum wrote:
>>>> When I open a new xterm, and say ulimit -a, I get:
>>>> stack size (kbytes, -s) 512
>
> I agree with the others. Based on tests on my system 512 kbytes is unusually
> low for a stack size limit and does not seem to be the default. I'm running
> MacOS 10.10.5 and both my xterms and Terminal.app default to a stack size
> limit of 8192K.
>
> To be more specific, they default to a soft limit of 8192K. The hard limit
> is 65532K:
>
> sh-3.2$ ulimit -Hs
> 65532
>
> The way these limits work is that a process is allowed to increase or
> decrease the soft limit at will as long as it does not set the soft limit to
> exceed the hard limit. For anyone but the superuser the hard limit may only
> be decreased, and once decreased may never be increased again by that process
> or by any of its children.
>
> Note these words in "man sh" where it describes the operation of the built-in
> ulimit command: "If neither -H nor -S is specified, both the soft and hard
> limits are set." This is likely why you are only able to change the stack
> limit once after opening Terminal: you are not specifying -S as part of the
> ulimit command so both soft and hard limits are being changed.
>
> I agree with Tom that what has likely happened to you is that some
> initialization script that you run in the process of getting a shell running
> in your xterm (perhaps some script involved in starting up your X windows
> environment) has a ulimit command in it to set the stack size limit to 512k.
> Because this command was not given the -S parameter, both the soft and the
> hard limits were set to 512k and the shell process that inherits this limit
> is not allowed to increase it.
>
> You can confirm that the hard limit has also been changed to 512k by giving
> the "ulimit -a -H" command on your system.
>
> Mike
>
>>
>>> I’m running a Mac mini at 10.6.8, Darwin Kernel Version 10.8.0, and a
>>> MBP at 10.11.6, Darwin Kernel Version 15.6.0. Without me doing anything
>>> other than exec’ing a ksh both give me a stack size of 8192K. A
>>> ‘Terminal’ window gives the same.
>>
>> Yes, I get the same results as David; also
>>
>> $ ulimit -a -H
>> core file size (blocks, -c) unlimited
>> data seg size (kbytes, -d) unlimited
>> file size (blocks, -f) unlimited
>> max locked memory (kbytes, -l) unlimited
>> max memory size (kbytes, -m) unlimited
>> open files (-n) unlimited
>> pipe size (512 bytes, -p) 1
>> stack size (kbytes, -s) 65532
>> cpu time (seconds, -t) unlimited
>> max user processes (-u) 1064
>> virtual memory (kbytes, -v) unlimited
>>
>> which shows (and experimentation confirms) that I can set the stack size
>> limit to anything under 64M.
>>
>> There's some useful info here
>>
>> https://developer.apple.com/library/content/qa/qa1419/_index.html
>>
>> which suggests that a 512K stack is what macOS defaults to for a
>> pthread. I doubt your shell per se would have become threaded,
>> but maybe it was launched from a thread of a multithreaded program.
>> I wonder if you have anything unusual in your ~/.bashrc, X startup
>> scripts, etc.
>>
>> regards, tom lane
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