RFR(xs): 8153876: Replace 4K stack allocations with Resource allocations

[harold seigel]

Hi Calvin,

Methods that allocate memory using NEW_RESOURCE_ARRAY and do not have 
ResourceMarks probably want to return the allocated memory to their 
caller.  I think that most of the places where you added 
NEW_RESOURCE_ARRAY allocations also should have ResourceMarks.

ResourceMarks should be added to classLoader.cpp at lines 346, 511, and 
753.  If THREAD is available then please add the ResourceMarks as 
ResourceMark rm(THREAD);.

Thanks, Harold


On 6/3/2016 2:06 PM, Calvin Cheung wrote:
> Hi David,
>
> Thanks for your review.
>
> On 6/2/16, 6:05 PM, David Holmes wrote:
>> Hi Calvin,
>>
>> On 3/06/2016 9:13 AM, Calvin Cheung wrote:
>>>
>>> Please review this small fix for replacing some of the array
>>> declarations with the resource allocation macros.
>>
>> If you add a resource allocation don't you also need to ensure there 
>> is a ResourceMark to clean it up again?
> I looked at some of the existing usage and none of them has a 
> ResourceMark.
> One example is in Arguments::build_resource_string().
>
>>
>> And what is the overhead of using resource allocation versus stack 
>> allocation? A lot of this seems to be in startup code.
> Since my fix touches the ctw_visitor() in classLoader.cpp, I tried to 
> use the -XX:+CompileTheWorld to see if there's any difference in perf 
> before and after the fix.
>
> I modified the function so that it only ran a limited number of 
> iterations. For a full run, it took more than 7 hrs.:
> CompileTheWorld : Done (41453 classes, 518964 methods, 25723180 ms)
>
> 100 iterations
> ------------
> no fix
> ======
> CompileTheWorld : Done (103 classes, 2096 methods, 66605 ms)
> CompileTheWorld : Done (103 classes, 2096 methods, 67171 ms)
> CompileTheWorld : Done (103 classes, 2096 methods, 66376 ms)
>
> with fix
> ========
> CompileTheWorld : Done (103 classes, 2096 methods, 66694 ms)
> CompileTheWorld : Done (103 classes, 2096 methods, 66358 ms)
> CompileTheWorld : Done (103 classes, 2096 methods, 66622 ms)
>
>
>
> 300 iterations
> ------------
> no fix
> ------
> CompileTheWorld : Done (321 classes, 4484 methods, 145322 ms)
> CompileTheWorld : Done (321 classes, 4484 methods, 144472 ms)
> CompileTheWorld : Done (321 classes, 4484 methods, 144229 ms)
>
> with fix
> --------
> CompileTheWorld : Done (321 classes, 4484 methods, 144748 ms)
> CompileTheWorld : Done (321 classes, 4484 methods, 145070 ms)
> CompileTheWorld : Done (321 classes, 4484 methods, 144773 ms)
>
> So the times are pretty much the same with and without the fix.
>
> Below is the disassembly of the NEW_RESOURCE_ARRAY:
>  511                  char* path = NEW_RESOURCE_ARRAY(char, 
> JIMAGE_MAX_PATH);
> 00007ffff6736f7d:   mov $0x1000,%eax
> 00007ffff6736f82:   mov $0x0,%esi
> 00007ffff6736f87:   mov %rax,%rdi
> 00007ffff6736f8a:   callq 0x7ffff7079ca0 
> <_Z23resource_allocate_bytesmN17AllocFailStrategy13AllocFailEnumE>
> 00007ffff6736f8f:   mov %rax,-0x10(%rbp)
>>
>>> bug: https://bugs.openjdk.java.net/browse/JDK-8153876
>>> webrev: http://cr.openjdk.java.net/~ccheung/8153876/webrev.00/
>>
>> src/share/vm/memory/metaspaceShared.cpp
>>
>> This change seems unnecessary - we don't have stackoverflow concerns 
>> when doing a dump.
> I was thinking the same. I will revert the change.
>
> thanks,
> Calvin
>>
>> Thanks,
>> David
>>
>>> Testing:
>>>     JPRT
>>>     non-colo "quick" tests
>>>
>>> thanks,
>>> Calvin