RFR: 7160924: jvmti: GetPhase returns incorrect phase before VMInit event is issued

[Karen Kinnear]

Summary - code change looks good.

thanks,
Karen

On Apr 12, 2012, at 10:03 AM, Karen Kinnear wrote:

> Dmitry,
> 
> I hear your point, there is a comment in the VM Initialization Event that "In the case of VM start-up
> failure, this event will not be sent".
> 
> That said, the goal of the VM initialization event is to inform the agent that it is free
> to call any JNI or JMVTI function. Many agents want to be able to start tracking the VM as early as possible.
> 
> So there is a trade-off in how early you send this event and risks of VM failures after we send it.
> To maximize benefits to users of the API, the current trade-off is to declare the VM initialized, i.e. in live phase,
> and to post the VM Initialization event  as soon as we meet the agents' needs.
> 
> Yes, it is possible for the VM to exit later, both on additional subsystem startup operations and of course
> due to things like out of memory errors at any time. So the "consistency" is that if we have a failure
> in starting up the VM for the operations critical to jvmti agents, we exit without sending the event. For
> failures later during startup and beyond, we don't. Bootstrapping is a very delicate process and 
> we want to optimize for the agents starting as early as they can for the success cases.
> 
> While longer term we would like to improve our ability to recover from some of the memory errors,
> I think the trade-off of empowering the agents to be functional as early as we can is the right balance
> at this time.
> 
> So - I would support the bug fix as is.
> 
> thanks,
> Karen
> 
> On Apr 12, 2012, at 9:12 AM, Dmitry Samersoff wrote:
> 
>> Rickard,
>> 
>> As far as I understand the code, after your changes we will
>> post JVMTI event
>> 
>> JvmtiExport::post_vm_initialized();
>> 
>> ever if later JVM aborts on some error.
>> 
>> I'm not sure it's a good idea because in couple of other
>> places we abort VM without sending the event, so
>> behavior of agent become inconsistent.
>> 
>> -Dmitry
>> 
>> 
>> 
>> On 2012-04-12 16:12, Rickard Bäckman wrote:
>>> Hi,
>>> 
>>> can I get review for this small change? The issue is that if we are
>>> running tracing startup code inbetween setting the phase to
>>> JVMTI_PHASE_LIVE and posting the VMInit event.
>>> 
>>> Webrev:
>>> http://cr.openjdk.java.net/~rbackman/7160924/webrev/
>>> 
>>> CR: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7160924
>>> 
>>> Thanks
>>> /R
>> 
>> 
>> -- 
>> Dmitry Samersoff
>> Java Hotspot development team, SPB04
>> * There will come soft rains ...
>