RFR: JDK-8145788: JVM crashes with -XX:+EnableTracing

[Yasumasa Suenaga]

Hi David,

>>     1. Initialize JavaThread before calling apply_ergo() in create_vm().
> 
> That is not likely to be an option - it would likely be far too
> disruptive to the initialization sequence.

Agree. Thus I choose 2.

> We will have to wait for the tracing experts to have a good look at
> this.

I'm waiting that the tracing experts join this discussion.


Thanks,

Yasumasa


On 2015/12/23 13:20, David Holmes wrote:
> Hi Yasumasa,
> 
> On 23/12/2015 11:49 AM, Yasumasa Suenaga wrote:
>> Hi David,
>>
>> I've added callstack when JVM crashed:
>>     https://bugs.openjdk.java.net/browse/JDK-8145788?focusedCommentId=13880225&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13880225
> 
> Thanks for that.
> 
>> This crash occurrs in Arguments::apply_ergo() in Threads::create_vm().
>> apply_ergo() calls before JavaThread initialization.
>>
>> I think that TraceEvent can avoid crash with two approach:
>>
>>     1. Initialize JavaThread before calling apply_ergo() in create_vm().
> 
> That is not likely to be an option - it would likely be far too
> disruptive to the initialization sequence.
> 
>>     2. Avoid crash at TraceEvent when it is called before JavaThread initialization.
> 
> Or don't call it at all.
> 
> We will have to wait for the tracing experts to have a good look at
> this. We end up in code that is not expecting to be run before more of
> the VM is initialized, so we have to look at what else may be being
> assumed and then decide whether to handle the situation or avoid it.
> 
> Thanks,
> David
> 
>>
>> Thanks,
>>
>> Yasumasa
>>
>>
>> On 2015/12/22 21:19, David Holmes wrote:
>>> On 19/12/2015 1:50 AM, Yasumasa Suenaga wrote:
>>>> Hi all,
>>>>
>>>> I encountered JVM crash when I passed -XX:+EnableTracing.
>>>>
>>>>      I checked core image, it crashed in EventBooleanFlagChanged::writeEvent()
>>>>      which is called by Arguments::apply_ergo() because thread had not been
>>>>      initialized. (JVM seems to log changing GC algorithm to G1.)
>>>
>>> This seems like a logic error to me - something is trying to happen too
>>> early during VM initialization. We need to look at exactly what we are
>>> trying to do here, not just work around the crash.
>>>
>>> David
>>> -----
>>>
>>>>      writeEvent() uses ResourceMark. Default constructor of ResourceMark uses
>>>>      ResourceArea in current thread. So ResourceMark in writeEvent() should
>>>>      pass valid ResourceArea.
>>>>
>>>> I think this issue is in traceEventClasses.xsl .
>>>> However, my environment (GCC 5.3.1 on Fedora23) cannot build it because
>>>> -Werror=maybe-uninitialized was occurred.
>>>> So I also fixed them together.
>>>>
>>>> I've uploaded webrev. Could you review it?
>>>>       http://cr.openjdk.java.net/~ysuenaga/JDK-8145788/webrev.00/
>>>>
>>>> I'm jdk9 committer, however I cannot access JPRT.
>>>> So I need a sponsor.
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Yasumasa
>>>>