CSR Review: 8189423: Add option to disable stack overflow checking in primordial thread for use with JNI_CreateJavaJVM

[Robbin Ehn]

On 10/17/2017 12:29 PM, David Holmes wrote:
> On 17/10/2017 7:28 PM, Robbin Ehn wrote:
>>> My understanding from prior discussion (ie when we fixed the 2MB 
>>> stack limit) is that it doesn't work for them to use a new thread for 
>>> the JVM. The change to support anything but unlimited stack size also 
>>> helped (and the 8M limit when 'unlimited' is tolerable) but really 
>>> they just want a simple way to say "please don't bother with stack 
>>> guards, I can deal with that myself".
>>
>> Is there a problem I'm not seeing to extends this to all attaching 
>> threads?
>> E.g. -XX:+DisableAttachingThreadGuardPages (more useful option I would 
>> say)
> 
> Yes - that allows it to impact all of our launchers as well - not 
> something I want to allow for. It opens the door for a myriad of bug 
> reports if people use this flag without understanding it's consequences.
> 
> The aim here is to solve a specific problem, not introduce new ways to 
> break things.

First, since this is broken, you would fix the issue with different 
stacksizes.

And secondly, I think the solution to that is to move all 'text' options 
to the launcher and have the CreateVM taking a data structure with 
pre-parsed options. And let the launcher choose which options to expose 
to the end-user. Meaning our own java launcher would never expose this 
option. (but this is much bigger discussion)

Would the option would skip adding guard to any other thread calling 
CreateVM?
If not, have the option really the correct name?

E.g. -XX:+DisableCreateVMThreadGuardPages ?

Thanks, Robbin

> 
> David
> 
>> Thanks, Robbin
>>
>>>
>>> This is intended to be a very simple, very specific proposal. I 
>>> suppose it could be flagged as "experimental" if we wanted the 
>>> flexibility to do something different later. But I don't see that 
>>> being on the cards.
>>>
>>> Cheers,
>>> David
>>>
>>>>
>>>> Thanks Robbin
>>>>
>>>>>
>>>>> Kind Regards, Thomas
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Oct 17, 2017 at 9:22 AM, David Holmes 
>>>>> <david.holmes at oracle.com>
>>>>> wrote:
>>>>>
>>>>>> CSR: https://bugs.openjdk.java.net/browse/JDK-8189423
>>>>>>
>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8189170
>>>>>>
>>>>>> Could I please have a reviewer for this CSR request so I can 
>>>>>> fast-track it.
>>>>>>
>>>>>> Comments on the proposal are of course welcome.
>>>>>>
>>>>>> Thanks,
>>>>>> David
>>>>>>