loss of cause??

[Kirk Pepperdine]

Hi Scott,

I don't think I've every talked about a standardized log format. I don't see how you could create one. However there are things you could do to make it easier to parse. Moving to XML wouldn't be one of my favourite choices. However you are correct in saying that the loosely structured log format that changes and takes on bugs from one build to the next is a problem. GC logging is the absolute best way to know whats going on and it provides the highest quality information for tuning purposes. It's easy to collect and it provides a whole hosts of values. For example, I can detect poor testing regimes by looking at the data, I've debugged strange memory conditions, found problems with frameworks. You simply cannot do these deeper types of analysis with any of the other sources of info about the collectors.

I'll take the weak formatting.. I can work with it but this rejiggering of the format for some what arbitrary reasons is a problem. In this case I can see the need to be an alignment for 8. However, I wish the alignment didn't come with this regression and one has to ask, how come the output is different on Window, Linux and OSX for the same build?

Regards,
Kirk

On 2013-10-11, at 12:16 AM, "STIRLING, SCOTT" <ss4766 at att.com> wrote:

> I thought there was a JSR to standardize on the log format, or had heard that a couple years ago at JavaOne in SFO. Might've been at one of Kirk's presentations, if I recall! I remember asking about it. IBM, for example, at least has an XML format to the JVM GC log so you can write tools around a parseable DOM -- but Sun, for years and years, has had this ad hoc, increasingly difficult to parse, loosely structured log format that changes regularly. It's kind of out of control ...
> 
> FWIW,
> Scott Stirling
> AT&T, Boston
> 
> -----Original Message-----
> From: hotspot-gc-dev-bounces at openjdk.java.net [mailto:hotspot-gc-dev-bounces at openjdk.java.net] On Behalf Of Kirk Pepperdine
> Sent: Thursday, October 10, 2013 4:20 PM
> To: Mikael Gerdin
> Cc: hotspot-gc-dev at openjdk.java.net openjdk.java.net
> Subject: Re: loss of cause??
> 
> Hi Mikael,
> 
> Thanks for the response. I'm aware of the flag. But more importantly I want, and I think I can speak for other, is for the log formats to remain stable. These things are painful enough to parse without having to compensate for variations not only across builds but across different OS'es.
> 
> Kind regards,
> Kirk Pepperdine
> 
> On 2013-10-10, at 4:00 PM, Mikael Gerdin <mikael.gerdin at oracle.com> wrote:
> 
>> On 10/10/2013 03:46 PM, Pierre Laporte wrote:
>>> This is also true for Linux :
>>> http://www.pingtimeout.fr/2013/08/gc-log-format-change.html
>> 
>> If you want the GC causes for all gcs in 7u40 please use -XX:+PrintGCCause
>> 
>> /Mikael
>> 
>>> 
>>> 
>>> On Thu, Oct 10, 2013 at 3:30 PM, Kirk Pepperdine <kirk at kodewerk.com
>>> <mailto:kirk at kodewerk.com>> wrote:
>>> 
>>>   Hi all,
>>> 
>>>   I've just noticed this in a GC log.
>>> 
>>>   642.015: [Full GC [PSYoungGen: 1904K->0K(79360K)] [ParOldGen:
>>>   337438K->338524K(442368K)] 339342K->338524K(521728K) [PSPermGen:
>>>   13239K->13239K(21504K)], 4.4455297 secs] [Times: user=7.94 sys=0.02,
>>>   real=4.44 secs]
>>> 
>>> 
>>>   This collection was triggered by a call to System.gc().
>>> 
>>>   More info
>>>   D:\dev\>"C:\Program Files\Java\jdk1.7.0_40\bin\java" -version
>>>   java version "1.7.0_40"
>>>   Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
>>>   Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)
>>> 
>>>   Flags used -Xloggc:gc.log -XX:+PrintGCDetails
>>> 
>>> 
>>>   Same app running in OSX produces;
>>> 
>>>   2.435: [Full GC (System) [PSYoungGen: 32K->0K(24064K)] [ParOldGen:
>>>   3666K->3666K(54976K)] 3698K->3666K(79040K) [PSPermGen:
>>>   9620K->9620K(22272K)], 0.0311970 secs] [Times: user=0.06 sys=0.00,
>>>   real=0.03 secs]
>>> 
>>>   Obviously triggered by a full GC
>>> 
>>>   flash-2:kirk$ java -version
>>>   java version "1.7.0_40"
>>>   Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
>>>   Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)
>>> 
>>>   Flags used -Xloggc:gc.log -XX:+PrintGCDetails
>>> 
>>>   I've not checked for this on Linux yet.
>>> 
>>>   So, it looks as though the (System) has been lost on windows?
>>> 
>>>   Regards,
>>>   Kirk
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> --
>>> 
>>> Pierre Laporte
>>> @pingtimeout <https://twitter.com/pingtimeout>
>>> pierre at pingtimeout.fr <mailto:pierre at pingtimeout.fr>
>>> http://www.pingtimeout.fr/
>> 
>