PING: RFR: JDK-8155730: HeapInfoDCmd should get Heap_lock

[Erik Helin]

On 2016-06-02, Yasumasa Suenaga wrote:
> PING: Could you review it?
> 
> >>  http://cr.openjdk.java.net/~ysuenaga/JDK-8155730/webrev.02/

This will not work - what if the VM crashes while holding the HeapLock?

Erik

> Yasumasa
> 
> 
> On 2016/05/17 19:19, Yasumasa Suenaga wrote:
> >PING: Could you review it?
> >I need review from GC folks.
> >
> >>  http://cr.openjdk.java.net/~ysuenaga/JDK-8155730/webrev.02/
> >
> >
> >Thanks,
> >
> >Yasumasa
> >
> >
> >On 2016/05/10 22:25, Yasumasa Suenaga wrote:
> >>On 2016/05/10 16:48, David Holmes wrote:
> >>>On 9/05/2016 10:34 PM, Yasumasa Suenaga wrote:
> >>>>Hi David,
> >>>>
> >>>>>Taking locks during VMError handling is problematic - we're executing
> >>>>>from a signal handler and the VM is crashing. Much of what we do from
> >>>>>VMError is "best effort".
> >>>>
> >>>>I will remove MutexLocker from VMError::report().
> >>>>But I added assert_locked_or_safepoint(Heap_lock) in each CollectedHeap.
> >>>>If we remove Heap_lock from VMError::report(), fastdebug HotSpot is failed
> >>>>when it prints heap info to hs_err log.
> >>>>Should I remove assert_locked_or_safepoint()?
> >>>
> >>>Yes I think you need to do this.
> >>
> >>I removed them in new webrev:
> >>
> >>  http://cr.openjdk.java.net/~ysuenaga/JDK-8155730/webrev.02/
> >>
> >>>>VMError::print_vm_info() calls from VMInfoDCmd::execute() only.
> >>>>So I think we should take Heap_lock at this function.
> >>>>Or should we take Heap_lock at VMInfoDCmd::execute() ?
> >>>
> >>>If this is called from a DCmd only then I think the lock can be taken in print_vm_info().
> >>
> >>I grep'ed HotSpot source, print_vm_info() is called from DCmd only.
> >>
> >>>Need GC folk to add their weight here.
> >>
> >>I'm waiting reviewer from GC folks :-)
> >>
> >>
> >>Thanks,
> >>
> >>Yasumasa
> >>
> >>
> >>>Thanks,
> >>>David
> >>>
> >>>>
> >>>>Thanks,
> >>>>
> >>>>Yasumasa
> >>>>
> >>>>
> >>>>On 2016/05/09 21:26, David Holmes wrote:
> >>>>>On 9/05/2016 10:20 PM, Yasumasa Suenaga wrote:
> >>>>>>Hi all,
> >>>>>>
> >>>>>>I've sent review request for JDK-8155730.
> >>>>>>However, I found caller of Universe::heap()->print_*() in vmError.cpp .
> >>>>>>Thus I added MutexLocker(Ex) for Heap_lock to VMError::report() and
> >>>>>>VMError::print_vm_info().
> >>>>>
> >>>>>Taking locks during VMError handling is problematic - we're executing
> >>>>>from a signal handler and the VM is crashing. Much of what we do from
> >>>>>VMError is "best effort".
> >>>>>
> >>>>>David
> >>>>>
> >>>>>>Could you review again?
> >>>>>>
> >>>>>>  http://cr.openjdk.java.net/~ysuenaga/JDK-8155730/webrev.01/
> >>>>>>
> >>>>>>
> >>>>>>>This needs to be reviewed by the GC folk not runtime. Please direct
> >>>>>>>followups to hotspot-gc-dev.
> >>>>>>
> >>>>>>Thanks, David!
> >>>>>>
> >>>>>>
> >>>>>>Yasumasa
> >>>>>>
> >>>>>>
> >>>>>>On 2016/05/06 13:11, David Holmes wrote:
> >>>>>>>Hi Yasumasa,
> >>>>>>>
> >>>>>>>This needs to be reviewed by the GC folk not runtime. Please direct
> >>>>>>>followups to hotspot-gc-dev.
> >>>>>>>
> >>>>>>>Thanks,
> >>>>>>>David
> >>>>>>>
> >>>>>>>On 30/04/2016 12:05 AM, Yasumasa Suenaga wrote:
> >>>>>>>>Hi all,
> >>>>>>>>
> >>>>>>>>This review request is related to [1].
> >>>>>>>>
> >>>>>>>>HeapInfoDCmd calls CollectedHeap::print_on().
> >>>>>>>>However, its call does not get Heap_lock.
> >>>>>>>>
> >>>>>>>>Heap_lock should be gotten from all heap operations.
> >>>>>>>>
> >>>>>>>>I uploaded webrev for this issue.
> >>>>>>>>Could you review it?
> >>>>>>>>
> >>>>>>>>  http://cr.openjdk.java.net/~ysuenaga/JDK-8155730/webrev.00/
> >>>>>>>>
> >>>>>>>>I cannot access JPRT.
> >>>>>>>>So I need a sponsor.
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>Thanks,
> >>>>>>>>
> >>>>>>>>Yasumasa
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>[1]
> >>>>>>>>http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2016-April/019257.html
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>