RFR(XS): 8204652: [aix] fix thread stack allocation, too big stack sizes not recognized

[Thomas Stüfe]

Hi Goetz,

On Sun, Jun 10, 2018 at 9:11 PM, Lindenmaier, Goetz
<goetz.lindenmaier at sap.com> wrote:
> Hi Thomas,
>
> The stack is started with 192k.  See the output:
>

Ah you are right. With 64K pages this would not be enough to establish
red/yellow zones and still have breathing space left.

> bash-4.4$ ~/oJ/vms/aix_j-1/bin/java -XX:CompilerThreadStackSize=8000000000000
> [1.482s][warning][os,thread] The compiler thread stack size specified is invalid: 8000000000000k
> [1.483s][warning][os,thread] Failed to start thread - pthread_create failed (22=EINVAL) for attributes: stacksize: 192k, guardsize: 4k, detached.
> Error occurred during initialization of VM
> java.lang.OutOfMemoryError: unable to create native thread: possibly out of memory or process/resource limits reached
>
> I think the output is not that bad ...

See my mail to David: I think the output is misleading, since
pthread_create() did not even run. So, "pthread_create failed" is
wrong.

Best Regards, Thomas

>
> Best,
>   Goetz.
>
>> -----Original Message-----
>> From: Thomas Stüfe <thomas.stuefe at gmail.com>
>> Sent: Sunday, June 10, 2018 7:33 PM
>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
>> Cc: hotspot-runtime-dev at openjdk.java.net
>> Subject: Re: RFR(XS): 8204652: [aix] fix thread stack allocation, too big stack
>> sizes not recognized
>>
>> Hi Goetz,
>>
>> I see what you intent to do, but I think we need to think about error
>> handling a bit more. The pattern here (which was broken you try to fix
>> it with this patch) is that we try, sequentially:
>>
>> - pthread_attr_setstacksize()
>>
>> - if ok-so-far pthread_attr_setguardsize
>>
>> - if ok-so-far pthread_ceate
>>
>> - logging and error handling
>>
>>
>> Problem with that is that in the end, we log information about a
>> failing thread creation, printing errno as if pthread_create() failed,
>> but that errno may have come actually from one of the preceeding OS
>> calls. So the error message would be misleading.
>>
>> I think it would be better to handle errors of each system call explicitly:
>>
>> pthread_attr_setstacksize()
>> if failed
>>    - log out "pthread_attr_setsize failed" and errno
>>    - [ also: optionally decide what to do: failing thread creation?
>> retry with a default stack size? ]
>>    - return false
>>
>> pthread_attr_setguardsize()
>> if failed
>>    - log out "pthread_attr_setguardsize failed" and errno
>>    - decide what to do - ignore? assert? fail thread creation? Should
>> we even care?
>>    - return false
>>
>> and then call pthread_create with the existing error handling as follow up.
>>
>> What do you think?`
>>
>> (Also, if pthread_attr_setstacksize() fails, should the thread not be
>> created with the pthread default stack size, which should be ~2MB? Why
>> is that stack tiny?)
>>
>> Best Regards, Thomas
>>
>>
>> On Sun, Jun 10, 2018 at 5:33 PM, Lindenmaier, Goetz
>> <goetz.lindenmaier at sap.com> wrote:
>> > Hi,
>> >
>> > This fixes a crash in thread creation with too big stack sizes
>> > http://cr.openjdk.java.net/~goetz/wr18/8204652-aixHugeStacksCrash/01/
>> > Please review.
>> >
>> > For Java and Compiler threads the return code of
>> pthread_attr_setstacksize
>> >  is overwritten. If pthread_attr_setstacksize does not succeed, a tiny
>> >  stack size with not enough space for the yellow/red pages is allocated.
>> >  VM crashes with SIGSEGV right away.
>> >
>> > Best regards,
>> >   Goetz