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List:       openjdk-serviceability-dev
Subject:    Re: RFR: JDK-8145788: JVM crashes with -XX:+EnableTracing
From:       Yasumasa Suenaga <yasuenag () gmail ! com>
Date:       2015-12-23 14:25:43
Message-ID: 567AAEE7.1060806 () gmail ! com
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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
> > > > 


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