JIT and invalidation

[Remi Forax]

On 02/17/2014 08:53 AM, Jeroen Frijters wrote:
> Hi Rémi,
>
> I believe this is not actually safe. There is no guarantee that when SwitchPoint.invalidateAll() returns that all calls to GET_BYTE or PUT_BYTE that were in flight have completed.
>
> Regards,
> Jeroen

yes, you're right,
I've forgotten to say that this code is Hotspot specific.

So let me re-phrase, I believe this code is safe if the VM is Hotspot 
because
invalidation is done at a safepoint so no GET_BYTE/PUT_BYTE can be in 
flight.

Rémi

>
>> -----Original Message-----
>> From: mlvm-dev-bounces at openjdk.java.net [mailto:mlvm-dev-
>> bounces at openjdk.java.net] On Behalf Of Remi Forax
>> Sent: Sunday, February 16, 2014 22:54
>> To: Da Vinci Machine Project
>> Subject: JIT and invalidation
>>
>> Hi John, Hi Christian, Hi all,
>> I don't know if you can test this little code, but when I run it on my
>> laptop (linux 64bits) it can terminate in 45s or 2 minutes, it seems
>> that it depends on the order the JIT compiles the method handles.
>>     https://gist.github.com/forax/9041030
>>
>> Sometimes it also PrintCompilation can also prints 'COMPILE SKIPPED:
>> invalid non-klass dependency'.
>>
>> BTW, the code allows to safely* map and unmap a 32G file without not
>> always paying the cost of the runtime check that test if the array is
>> unmaped or not :)
>>
>> cheers,
>> Rémi
>> * I believe.
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