RFR: 8203948: Expand JVMTI callback notion of "internal threads"

[coleen.phillimore at oracle.com]

On 5/30/18 10:18 PM, David Holmes wrote:
> Hi Kim,
>
> I guess I'd like this more if NamedThread were called something like 
> InternalThread as that captures the actual commonality of these 
> threads (we don't really care they they have names!). But that's not 
> your fault.
>
> I'm still tempted to just remove the check altogether now there is 
> only one thread we're excluding - do we really need to guard against 
> the WatcherThread using this code?

Yes our discussion in the office went something like this.   Not sure if 
it's guarding against the WatcherThread or what this code is thinks it's 
guarding against.

Coleen

>
> But its fine to push as-is.
>
> Thanks,
> David
>
> On 31/05/2018 2:28 AM, Kim Barrett wrote:
>> Please review this change to JVMTI to relax some restrictions on where
>> some functions may be called.  Presently they are restricted to being
>> called from either a Java thread, the VM thread, or a thread for which
>> is_ConcurrentGC_thread() returns true (e.g. ConcurrentGCThreads and
>> AbstractGangWorkers (if the containing WorkGang is configured as
>> concurrent).
>>
>> We now allow these functions to be called for either a Java thread or
>> a Named thread, e.g. any of the VM thread, ConcurrentGCThreads, or
>> WorkerThreads.  This allows the restricted functions to be called from
>> any WorkerThreads, rather than only AbstractGangWorkers in concurrent
>> WorkGangs.
>>
>> The change to jvmtiEnter.xsl affects the following generated
>> functions:
>> jvmti_Allocate
>> jvmti_Deallocate
>> jvmti_CreateRawMonitor
>> jvmti_DestroyRawMonitor
>> jvmti_RawMonitorEnter
>> jvmti_RawMonitorExit
>> jvmti_RawMonitorWait
>> jvmti_RawMonitorNotify
>> jvmti_RawMonitorNotifyAll
>> jvmti_GetTimerInfo
>> jvmti_GetTime
>> jvmti_SetEnvironmentLocalStorage
>> jvmti_GetEnvironmentLocalStorage
>>
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8203948
>>
>> Webrev:
>> http://cr.openjdk.java.net/~kbarrett/8203948/open.00/
>>
>> Testing:
>> Mach5 tier{1,2,3} and hs-tier{4,5}
>>
>> There are no tests that directly exercise the relaxed restrictions
>> yet.  We'll start hitting that as part of in-progress work to
>> parallelize WeakProcessor, which calls JvmtiExport::weak_oops_do,
>> which generates ObjectFree events, which uses the Raw Monitor API.
>>