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

[David Holmes]

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.

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
>>