RFR: JDK-8188312 Use CDS if present when running the Boot JDK during build

[Magnus Ihse Bursie]

On 2017-10-03 14:21, David Holmes wrote:
> Erik J. raises a good point in the bug report that 
> -XX:SharedArchiveFile=xxx should be used if we create the archive. The 
> build system has no business creating an archive inside the boot JDK.

Agree, that is a better solution. I was not aware of the 
-XX:SharedArchiveFile option.

Here's an updated webrev:
http://cr.openjdk.java.net/~ihse/JDK-8188312-use-CDS-for-bootjdk/webrev.02

I create the jsa file in configure-support, that way it can survive a 
"make clean".

/Magnus

>
> David
>
> On 3/10/2017 9:02 PM, David Holmes wrote:
>> Hi Claes,
>>
>> On 3/10/2017 8:48 PM, Claes Redestad wrote:
>>> Hi,
>>>
>>> -Xshare:auto silently ignores failures to map the shared archive and 
>>> should be safe to use. I think you're thinking of -Xshare:on which 
>>> will fail/abort the VM if mapping fails.
>>
>> Ah okay.
>>
>> In that case seems reasonable. But please test thoroughly across all 
>> platforms in JPRT.
>>
>> Thanks,
>> David
>>
>>> /Claes
>>>
>>>
>>> On 2017-10-03 12:28, David Holmes wrote:
>>>> Hi Magnus,
>>>>
>>>> As I just put in the bug report, it isn't quite this simple. You 
>>>> have to be able to tolerate/recover from failure to map the shared 
>>>> archive.
>>>>
>>>> Cheers,
>>>> David
>>>>
>>>> On 3/10/2017 8:24 PM, Magnus Ihse Bursie wrote:
>>>>> We should use CDS to minimize Java startup time during build. We 
>>>>> run multiple Java commands, and every second counts.
>>>>>
>>>>> On my machine, I get a ~3% build time speedup with this fix.
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8188312
>>>>> WebRev: 
>>>>> http://cr.openjdk.java.net/~ihse/JDK-8188312-use-CDS-for-bootjdk/webrev.01 
>>>>>
>>>>>
>>>>> /Magnus
>>>