8050044: (process) Increase reaper thread native stack size by a factor of 2

[Martin Buchholz]

Alright, we can abandon this change.  In practice, tests on different
platforms will usually catch SOE before users encounter it, because the
stacks are all almost identical.  Unless there is e.g. a hotspot bug that
causes thread local variables to be allocated inside the stack size instead
of outside.

Is there monitoring available that can warn when e.g. stack high-water mark
is ever more than 50%?


On Fri, Jul 18, 2014 at 7:40 AM, Rob McKenna <rob.mckenna at oracle.com> wrote:

> So doing a bit of homework should probably have been my first approach.
>
> Interestingly, we are never actually going to have only 32k allocated for
> the stack. The VM will allocate the os::Solaris|Linux|etc::min_stack_allowed
> size which is a minimum of 48k on some platforms but generally 64k+.
> Windows goes to the trouble of calculating the value based on the guard
> pages and some other variables.
>
> In effect, with the 32k value we're asking the (more specifically, our) VM
> to allocate the minimum possible stack which is calculated on a
> per-platform basis. Perhaps the "fix" for this bug should really just be a
> comment acknowledging that this is a minimum acceptable value and the VM
> will likely determine the actual size?
>
>     -Rob
>
>
> On 15/07/14 18:58, Martin Buchholz wrote:
>
>> The fear is that stack sizes and alignments have grown over time, and
>> thread stacks are acquiring things like guard pages, and those pages may
>> (incorrectly) end up getting included in the stack size.  I'm particularly
>> afraid of the hotspot guard page code.
>>
>> It may be worthwhile seeing how low you can make the stack size on popular
>> platforms before the jtreg tests for process fall over, then multiply by
>> 10
>> at least.
>>
>> We are approaching the 64-bit only era, when address space restrictions
>> won't be a problem (for a while)
>>
>>
>> On Tue, Jul 15, 2014 at 10:51 AM, roger riggs <roger.riggs at oracle.com>
>> wrote:
>>
>>  Hi Rob,
>>>
>>> Is there any evidence that needs more space?  Is there any way to tell
>>> how
>>> much of
>>> the existing 32k is being used?
>>> The reaper has very limited processing to do and there is one thread for
>>> every process spawned.
>>>
>>> Roger
>>>
>>>
>>>
>>> On 7/15/2014 1:46 PM, Rob McKenna wrote:
>>>
>>>  Hi folks,
>>>>
>>>> A very simple change suggested by Martin a while back in another review.
>>>> I'm just getting around to it now:
>>>>
>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8050044
>>>> webrev: http://cr.openjdk.java.net/~robm/8050044/webrev.01/
>>>>
>>>> Martins comments: http://mail.openjdk.java.net/
>>>> pipermail/core-libs-dev/2014-March/025943.html
>>>>
>>>>      -Rob
>>>>
>>>>
>>>>
>