RFR: 8151526: Print -Xlog configuration in the hs_err_pid file

[Coleen Phillimore]

On 4/1/16 4:45 AM, Marcus Larsson wrote:
> Hi,
>
> On 03/31/2016 08:08 PM, Max Ockner wrote:
>> (Replies in line)
>>
>> On 3/30/2016 9:31 AM, Thomas Stüfe wrote:
>>> Hi Max,
>>>
>>> Disclaimer: not a (R)eviewer.
>>>
>>> Do we really need a list of all tags and all decorators?
>>>
>> Just going by what we currently put in the hs_err file, I think this 
>> may be the first "Do we really need" we've ever asked for this type 
>> of change.
>>
>> All joking aside, I think it is a good idea to direct users toward 
>> proper UL usage whenever we have a chance.
>>
>>> Also: I assume what you print is the Log state as it is at the time 
>>> the hs-err file is printed. If logging was enabled/changed during 
>>> lifetime of the VM, e.g. with jcmd, would it be possible to see 
>>> that? At least a warning if logging was not enabled from the start on.
>>>
>> Would it be possible? Yes, but I think this would require a framework 
>> change. It does not look like any marks are made when the 
>> LogConfiguration changes during runtime, and we would need to record 
>> that in order to know what to print when we dump into hs_err.
>
> Yes, this would required the framework to keep some sort of log of 
> configuration changes. Is there value in knowing that the log 
> configuration changed since startup?
>

Actually, there's an Event logger that saves events and then we print 
the last 'n' events out in the hs_err file.  If you think this would be 
useful, please file an RFE.

Thanks,
Coleen


>>
>> Thanks,
>> Max
>>> Kind Regards, Thomas
>>>
>>>
>>>
>>>
>>> On Tue, Mar 29, 2016 at 9:00 PM, Max Ockner <max.ockner at oracle.com 
>>> <mailto:max.ockner at oracle.com>> wrote:
>>>
>>>     Hello,
>>>     Please review another Unified Logging change. They are almost
>>>     done, and we are serious this time.
>>>
>>>     bug: https://bugs.openjdk.java.net/browse/JDK-8151526
>>>     webrev: http://cr.openjdk.java.net/~mockner/8151526.01/
>>>     <http://cr.openjdk.java.net/%7Emockner/8151526.01/>
>>>
>
> LogConfiguration::describe() takes the ConfigurationLock, which might 
> be problematic for the error handler. I suppose the error handler 
> could potentially deadlock if its thread already holds the lock. 
> Unsure how to resolve this, because skipping to take the lock means 
> that we might crash due to another thread changing the configuration 
> as we read it.
>
> Thanks,
> Marcus
>
>>>
>>>     The logging configuration is now printed in each hs_err file. The
>>>     output is the same as you would see from -Xlog:logging=trace and
>>>     it is obtained from LogConfiguration::describe().
>>>
>>>     Below is a sample of the hs_err contents. The Logging info is
>>>     printed after VM Arguments and Whitebox, and before Environment
>>>     Variables.
>>>
>>>     VM Arguments:
>>>     java_command: Kaboom
>>>     java_class_path (initial): .
>>>     Launcher Type: SUN_STANDARD
>>>
>>>     Logging:
>>>     Available log levels: off, trace, debug, info, warning, error
>>>     Available log decorators: time (t), uptime (u), timemillis (tm),
>>>     uptimemillis (um), timenanos (tn), uptimenanos (un), hostname
>>>     (hn), pid (p), tid (ti), level (l), tags (tg)
>>>     Available log tags: alloc, age, barrier, biasedlocking, bot,
>>>     census, classhisto, classresolve, classinit, classload,
>>>     classloaderdata, classunload, classpath, compaction, cpu, cset,
>>>     defaultmethods, ergo, exceptions, exit, freelist, gc, heap,
>>>     humongous, ihop, itables, jni, liveness, logging, marking,
>>>     metaspace, modules, monitorinflation, os, phases, plab,
>>>     promotion, preorder, protectiondomain, ref, refine, region,
>>>     remset, safepoint, safepointcleanup, scavenge, scrub, stacktrace,
>>>     start, startuptime, state, stats, stringdedup, stringtable,
>>>     survivor, sweep, task, thread, tlab, time, verboseverification,
>>>     verify, vmoperation, vtables
>>>     Log output configuration:
>>>     #0: stdout all=off uptime,level,tags,
>>>     #1: stderr all=warning uptime,level,tags,
>>>
>>>     Environment Variables:
>>> JAVA_HOME=/scratch/mockner/UL/8151526/build/linux-x86_64-normal-server-fastdebug/images/jdk
>>> PATH=/home/mockner/tools/webrev:/bin:/usr/bin:/usr/local/bin:/usr/sbin:/home/mockner/bin:/home/mockner/linux/bin
>>>     SHELL=/bin/bash
>>>     OS=Linux
>>>
>>>
>>
>