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

[harold seigel]

Hi Calvin,

It looks good to me, also.

Thanks, Harold


On 6/5/2016 9:19 PM, David Holmes wrote:
> On 4/06/2016 9:10 AM, Calvin Cheung wrote:
>> Hi Harold, David,
>>
>> I've updated the webrev with ResourceMark and reverted the changes in
>> metaspaceShared.cpp.
>> http://cr.openjdk.java.net/~ccheung/8153876/webrev.01/
>
> Looks good.
>
> Thanks,
> David
>
>>
>> On 6/3/16, 12:06 PM, harold seigel wrote:
>>> 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.
>> Except for ClassPathDirEntry::open_stream(). The buffer will be added to
>> the ClassFileStream but the path is a local variable. So I've added
>> FREE_RESOURCE_ARRAY for path in several places.
>>>
>>> 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);.
>> Yes, they've been added in the updated webrev.
>>
>> I'll rerun some tests.
>>
>> thanks,
>> Calvin
>>
>>>
>>> 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
>>>