RFR: 8177845: Need a mechanism to load Graal

[Mandy Chung]

> On Apr 19, 2017, at 8:03 AM, Peter Levart <peter.levart at gmail.com> wrote:
> 
> Hi Alan,
> 
> On 04/19/2017 03:41 PM, Alan Bateman wrote:
>> On 19/04/2017 08:37, Peter Levart wrote:
>> 
>>> :
>>> 
>>> Note that Properties class is thread-safe, while HashMap isn't. But I think this should not be a problem here, as during initPhase1(), as far as I know, no threads apart from main thread are started yet (is this true?), so anyone accessing getSavedProperty(ies) will either be the main thread itself or a thread started afterwards, so there is a happens-before relationship.
>> The ReferenceHandler and Finalizer threads are started early, before initPhase1. However, both should immediately block and in the case of the Finalizer, await the completion of initPhase1 before polling.
>> 
>> -Alan
> 
> Just out of curiosity, what guarantees are there that no code before VM.saveAndRemoveProperties() ever executes Integer.valueOf(int) method for example? Note that this call is implicitly hidden in autoboxing of int(s)...
> 
> If this happens, then class initialization of Integer.IntegerCache may fail, because it is using VM.getSavedProperty():
> 
>    public static String getSavedProperty(String key) {
>        if (savedProps.isEmpty())
>            throw new IllegalStateException("Should be non-empty if initialized");
> 
>        return savedProps.getProperty(key);
>    }
> 
> Hm....

We should catch this issue and detect if VM.getSavedProperty is called when init level < 1 during early startup.

Mandy