7090324: gclog rotation via external tool

Kirk Pepperdine kirk at kodewerk.com
Tue Aug 14 09:26:53 UTC 2012


Hi Yasumasa,

I'm not sure that log file rotation is a part of this JEP. However I do have very serious concerns about this JEP in that it doesn't fix the problems that exist in current logging frameworks, it only mimics them.

Regards,
Kirk

On 2012-08-14, at 11:20 AM, Yasumasa Suenaga <suenaga.yasumasa at lab.ntt.co.jp> wrote:

> Hi Staffan,
> 
> May I ask you 2 questions about this JEP?
> 
> 1. One of goals of this JEP is defined as following:
>      "File rotation of log files by size (similar to what is available for GC logs today)"
>    My patch realizes log rotation by external trigger.
>    7090324 is included in this JEP?
>    (Is 7090324 included in "Logging can be configured dynamically at runtime via jcmd or MBeans" ? )
> 
> 2. I've posted a patch for "6950794: Make the GC log file name parameterized" .
>      http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2012-July/004758.html
>    Could you include this RFE in this JEP?
>    If we use log rotation, I think that name of logs is very important for log management.
> 
> 
> Thanks,
> 
> Yasumasa
> 
> 
> On 2012/08/14 16:50, Staffan Larsen wrote:
>> Hi Yasumasa,
>> 
>> This work should be done in the context of the Unified Logging JEP [1]. Unfortunately, that work has not yet started due to resource constraints. Comments on the proposal are welcome.
>> 
>> [1] http://openjdk.java.net/jeps/158
>> 
>> /Staffan
>> 
>> On 31 jul 2012, at 12:45, Yasumasa Suenaga <suenaga.yasumasa at lab.ntt.co.jp <mailto:suenaga.yasumasa at lab.ntt.co.jp>> wrote:
>> 
>>> Hi,
>>> 
>>> I've posted a patch for gc log rotation via jinfo tool last year.
>>> Then I received an email that essence of my patch will be implemented as
>>> "subcommands" of jcmd.
>>> 
>>> Now, jcmd is provided by OpenJDK. However, current jcmd does not seem to
>>> implement function of gclog rotation.
>>> 
>>> Will this RFE be implemented?
>>> 
>>> I need to rotate gclog which is synchronized with signal, cron, etc... on Linux.
>>> So, if this RFE is not implemented for a while, I would like to contribute
>>> patch for jcmd.
>>> 
>>> 
>>> Regards,
>>> 
>>> Yasumasa
>>> 
>>> 
>>> On 2011/09/29 21:15, James Melvin wrote:
>>>> Hi Yasumasa,
>>>> 
>>>> Thanks very much for your OpenJDK contribution! As part of the effort to
>>>> port JRockit features to HotSpot, we plan to introduce a consolidated
>>>> commandline serviceability tool (jcmd) to potentially replace many of
>>>> the existing tools in the bin directory, such as jmap, jstack, jinfo and
>>>> others. Over the next few update releases, we plan to add several jcmd
>>>> *subcommands* instead to accomplish specific tasks or affect the running
>>>> JVM instance. We'd like to use the essence of your contribution in one
>>>> of the jcmd subcommands (instead of extending jinfo) to ask the JVM to
>>>> begin rotating GC logs. We hope you find this attractive and hope you
>>>> will help review and perfect the change.
>>>> 
>>>> Thanks,
>>>> 
>>>> Jim Melvin
>>>> Sr. Engineering Manager
>>>> Oracle
>>>> 
>>>> 
>>>> 
>>>> On 9/26/11 6:38 AM, Yasumasa Suenaga wrote:
>>>>> (I've changed subject of this email to new RFE.)
>>>>> 
>>>>> This RFE is enhancement of current gclog implementation.
>>>>> So, I'd like to discuss about rotating gclog.
>>>>> 
>>>>> My customers need gclog rotation which is invoked by external trigger.
>>>>> So I've requested this RFE and made a patch.
>>>>> 
>>>>> 
>>>>> In many case on Linux, logfile is rotated by signal (e.g. SIGHUP) .
>>>>> The aim of this RFE is to synchronize gclog and the other logs.
>>>>> 
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> Yasumasa
>>>>> 
>>>>> (2011/09/22 20:55), Rainer Jung wrote:
>>>>>> On 22.09.2011 13:20, Dmitry Samersoff wrote:
>>>>>>> 
>>>>>>> Yasumasa,
>>>>>>> 
>>>>>>> On 2011-09-22 04:47, Yasumasa Suenaga wrote:
>>>>>>>> If we can think Java on Linux and Solaris only, syslog is best
>>>>>>>> solution.
>>>>>>>> However, Windows usually doesn't have syslog.
>>>>>>>> 
>>>>>>>> So, I think that gclog is needed for logging GC stats with platform
>>>>>>>> independent in realtime.
>>>>>>> 
>>>>>>> Windows has it's own logging API as reach as syslog is or ever better
>>>>>>> as well as numerous syslog implementations.
>>>>>>> 
>>>>>>> Native windows logging API was completely redesigned for Windows 2008
>>>>>>> server and now it allows for developers to send a structured events from
>>>>>>> theirs application.
>>>>>> 
>>>>>> AFAIK log rotation for loggc is already implemented though not
>>>>>> necessarily yet released. The change discussed here is about supporting
>>>>>> an externally generated rotation trigger, e.g. via a signal, instead of
>>>>>> only rotating by size or time via a startup parameter.
>>>>>> 
>>>>>> If you want support for syslog or Windows APIs included, it would be
>>>>>> best to start a new discussion.
>>>>>> 
>>>>>> A GC log for an application under load might easily produce a block of
>>>>>> about 1.5 KB size every few seconds. I seriously doubt, that the need
>>>>>> for log file rotation can be argued away by referring to syslog or
>>>>>> Windows log API as the correct solution.
>>>>>> 
>>>>>> The messages are not really line formatted, the format can vary a lot
>>>>>> (depending on the excat XX switches), the traffic can be quite high and
>>>>>> AFAIK the JVM writes it synchronously, so there must be absolutely no
>>>>>> risk in writing it out with very little latency. In addition, for
>>>>>> analysis, you wouldn't want to look at each event individually, but
>>>>>> instead process the whole file through a script or tool, which should
>>>>>> not depend on the output specifics of a platform specific log apparatus.
>>>>>> 
>>>>>> Regards,
>>>>>> 
>>>>>> Rainer
>>>>>> 
>>>>> 
>>> 
>> 
> 




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