RFC: JWarmup precompile java hot methods at application startup

[David Holmes]

Hi Yumin,

On 26/04/2019 2:07 am, yumin qi wrote:
> Hi,
> 
>    Apart from comments from compiler professionals can I have comments from
> runtime either? The changes mostly land in runtime area.

I have to question why the changes mostly land in runtime area! The 
high-level description of this feature does not sound like it depends on 
the runtime at all. The "recording" feature should just come from the 
JITs data; and the actual warmup should just be an interaction during VM 
initialization with the JIT. I don't see anything in the JEP to explain 
the actual design, and why it impacts on the runtime so much.

It also sounds like a selective Xcomp mode to me.

It even sounds very similar to Initialization-Time-Compilation (ITC) 
that we employed in Java Real-Time System:

https://docs.oracle.com/javase/realtime/doc_2.2u1/release/JavaRTSCompilation.html

Cheers,
David

> Thanks
> Yumin
> 
> On Tue, Apr 16, 2019 at 11:27 AM yumin qi <yumin.qi at gmail.com> wrote:
> 
>> HI,
>>
>>    Did anyone have comments for this version?
>>
>> Thanks
>> Yumin
>>
>> On Tue, Apr 9, 2019 at 10:36 AM yumin qi <yumin.qi at gmail.com> wrote:
>>
>>> Alan,
>>>    Thanks! Updated in same link:
>>>    http://cr.openjdk.java.net/~minqi/8220692/webrev-02/
>>>
>>>    Removed non-boot loader branch in nativeLookup.cpp.
>>>    Added jdk.jwarmup to boot loader list in make/common/Modules.gmk.
>>>    Tested again to make sure the new changes.
>>>
>>>    Thanks
>>>    Yumin
>>>
>>>
>>> On Tue, Apr 9, 2019 at 4:48 AM Alan Bateman <Alan.Bateman at oracle.com>
>>> wrote:
>>>
>>>> On 09/04/2019 07:10, yumin qi wrote:
>>>>>
>>>>>    Now the registerNatives is found when it looks up for native entry
>>>>> in lookupNative.cpp. I thought the class JWarmUp will be loaded by
>>>>> boot loader like Unsafe or WhiteBox, but I was wrong, it is loaded by
>>>>> app class loader so logic for obtaining its native entry put in both
>>>>> cases, boot loader and non boot loaders.
>>>>>
>>>> make/common/Modules.gmk is where BOOT_MODULES is defined with the list
>>>> of modules mapped to the boot loader.
>>>>
>>>> -Alan
>>>>
>>>