Basically we are hosting distributed systems for our clients. So we have several dozens of JVM per physical host, and several dozens of physical hosts. Moreover some clients are sometimes moved from one machine to another so having a single configuration file is a very huge requirement.
Having the file that rolls precisely at midnight is a nice to have. Having the rolling that happen a little later because of randomization can be accepted if it solve the performance issue (which stay pretty short, it's about 15 seconds during which we can experience a few hundreds of milliseconds long stalls but this is already too much in our industry ) Randomization is a common technique for that kind of issue, used in congestion avoidance in some network protocols for example (including Ethernet ). Having 2 or 3 jvm that roll at the same time is not a big deal, we have enough free cpu cycles for that. That's why randomization during a few minutes seems OK to me : we don't need to annihilate collisions, greatly reduce them is OK Basically I'm open to any solution as long as it can be deployed everywhere without any OS/shell dependant trick and it does not involve any kind of per JVM configuration. The patch I submitted is an option, but I'd be glad to use another option that match these requirements. Regards, Anthony Le 24 mars 2017 15:20, "Remko Popma" <remko.po...@gmail.com> a écrit : Actually, there is already something like this because Log4j2 configuration has some support for scripting. I would prefer to enhance that over building conditional constructs in the configuration. However, having to specify the exact rollover time for individual servers would result in a much more lengthy and involved configuration. Randomization is a commonly used technique to get roughly the same result without the inconvenience of precise configuration. I don't think it is such a bad idea. Sent from my iPhone > On Mar 24, 2017, at 19:35, Dominik Psenner <dpsen...@apache.org> wrote: > > What if a configuration could contain conditional statements? For instance: > > <Config> > <Define EnvironmentVariable="Hour" Value="12" /> > <Define EnvironmentVariable="Minute" Value="0" /> > <If EnvironmentVariable="JVM" Equals="JVM1"> > <Define EnvironmentVariable="Minute" Value="0" /> > </If> > <If EnvironmentVariable="JVM" Equals="JVM2"> > <Define EnvironmentVariable="Minute" Value="1" /> > </If> > <RollingFileAppender> > <RollingCondition> > <Cron Minute="$Minute" Hour="$Hour" DayOfMonth="*" Month="*" DayOfWeek="*" /> > </RollingCondition> > </RollingFileAppender> > </Config> > > Cheers > >> On 2017-03-24 11:08, Remko Popma wrote: >> I see what you are saying, but the use case is to have a single configuration, that is what drives the request. >> >> Sent from my iPhone >> >>> On Mar 24, 2017, at 17:22, Dominik Psenner <dpsen...@apache.org> wrote: >>> >>> Hi there, >>> >>> Cron proved itself very to be stable and usable over the past years. FWIW, I would not recommend to introduce a randomization algorithm. An application that does things random means that the application does things when nobody expects it to do so. Further it does not solve the problem. One just needs enough JVMs to roll around at the same time with a randomizer does not produce large enough values to spread the rolling over a larger amount of time. The available CPU is then quickly drain out. In my opinion, it's better to configure the several rollings to be delayed, meaning that JVM1 rolls at 12:00, JVM2 rolls at 12:01, ... >>> >>> Cheers, Dominik >>> >>>> On 2017-03-23 15:04, Anthony Maire wrote: >>>> https://issues.apache.org/jira/browse/LOG4J2-1855 >>>> https://github.com/apache/logging-log4j2/pull/68 >>>> >>>> Let me know if you want me to do some changes >>>> >>>> Regards, >>>> Anthony >>>> >>>> >>>> 2017-03-23 13:15 GMT+01:00 Anthony Maire <maire.anth...@gmail.com>: >>>> >>>>> Ok, I will open a jira ticket and provide a PR. >>>>> >>>>> Thanks for your input. >>>>> >>>>> Le 23 mars 2017 13:08, "Remko Popma" <remko.po...@gmail.com> a écrit : >>>>> >>>>>> I see what you mean now. I agree it's better to keep the rollover concept >>>>>> to mean file rename and compression that happen in sequence together. So >>>>>> the randomization affects when the _sequence_ is triggered, not just one >>>>>> part of the sequence. Makes sense. >>>>>> >>>>>> Sent from my iPhone >>>>>> >>>>>>> On Mar 23, 2017, at 16:28, Anthony Maire <maire.anth...@gmail.com> >>>>>> wrote: >>>>>>> Hi Remko >>>>>>> >>>>>>> My first idea was to have the rolling that triggers at the expected >>>>>> time, >>>>>>> and the compression that will be delayed. That's why I wanted the >>>>>> delayed >>>>>>> compression to occur before shutdown since the rolling already occurred. >>>>>>> >>>>>>> But I think that's a bad idea. First, it will lead to "fancy code" and I >>>>>>> would like to avoid it too. But the main issue is that this behavior >>>>>> should >>>>>>> impact only the time based triggering when combining several policy. So >>>>>> the >>>>>>> code should be related to the triggering policy and not to the rolling >>>>>>> strategy. >>>>>>> >>>>>>> So the best thing to do is to add some property on the timed base >>>>>>> triggering policy and let that class handle all the logic and delay the >>>>>>> triggering itself instead of the compression. >>>>>>> >>>>>>> Are you OK with that? >>>>>>> >>>>>>> Anthony >>>>>>> >>>>>>> Le 23 mars 2017 00:24, "Remko Popma" <remko.po...@gmail.com> a écrit : >>>>>>> >>>>>>> >>>>>>>> On Mar 23, 2017, at 1:06, Anthony Maire <maire.anth...@gmail.com> >>>>>> wrote: >>>>>>>> Thanks for these answers >>>>>>>> >>>>>>>> @Ralph : that was the kind of idea I had in mind : changing the >>>>>>>> RollingFileManager.asyncExecutor to be a ScheduledThreadPoolExecutor, >>>>>> and >>>>>>>> based on some configuration, submitting task to be executed after a >>>>>> random >>>>>>>> delay. However with this kind of approach, special treatment should be >>>>>>> made >>>>>>>> if the manager is stopped with some pending delayed tasks in it. >>>>>>> I'm okay with randomization except for this last bit about "special >>>>>>> treatment...". Let's not make it too fancy. If the manager is stopped >>>>>>> before it rolled over, then it didn't roll over, just like it works >>>>>>> currently. I don't see the point of adding extra logic to trigger a >>>>>>> rollover when the manager is stopped within the randomized time window. >>>>>>> >>>>>>>> @Matt : Cron policy can be a solution, but I don't know how to inject >>>>>> some >>>>>>>> random element in this to make the file roll at midnight + X random >>>>>>>> seconds. Since there is a lot of JVM to manage and some of them can be >>>>>>>> moved from a machine to another, I need to have a single log4j2.xml >>>>>> file >>>>>>>> for all environments. Moreover, our system administrators are >>>>>> reluctant to >>>>>>>> have something based on a shell-specific feature (such has the $RANDOM >>>>>>>> variable from bash) >>>>>>>> >>>>>>>> Anthony >>>>>>>> >>>>>>>> 2017-03-22 16:31 GMT+01:00 Ralph Goers <ralph.go...@dslextreme.com >: >>>>>>>> >>>>>>>>> These are separate JVMs, so having a single executor would be of no >>>>>> help. >>>>>>>>> I believe the only way to do what you are asking for is to add >>>>>>>>> configuration so that the asynchronous thread has a semi-random delay >>>>>>> when >>>>>>>>> it starts. >>>>>>>>> >>>>>>>>> Ralph >>>>>>>>> >>>>>>>>>> On Mar 22, 2017, at 7:58 AM, Greg Thomas <greg.d.tho...@gmail.com > >>>>>>>>> wrote: >>>>>>>>>>> One common issue we have with that framework (and I assume we can >>>>>> have >>>>>>>>> the >>>>>>>>>>> same with log4j2) is that all of our JVMs (we can have more than 50 >>>>>>>>> JVMs on >>>>>>>>>>> the same server in production) roll their file at midnight. >>>>>>>>>>> >>>>>>>>>>> When this happens, the system became often not usable for a few >>>>>> seconds >>>>>>>>>>> because of the simultaneous zipping of all the rolled files that >>>>>>>>> overload >>>>>>>>>>> the CPU (although zipping is done in a specific background thread). >>>>>>>>>> ISTR that with the most recent versions of log4j, these threads are >>>>>> in a >>>>>>>>>> thread pool so that they are properly shutdown at the right time. I >>>>>>>>> wonder >>>>>>>>>> if it's possible (or could be possible) to somehow inject a thread >>>>>> pool >>>>>>>>> in >>>>>>>>>> to log4j for this rollover, so that for you use case you could >>>>>> inject a >>>>>>>>>> single thread executor, so only one thread is ever compressing at a >>>>>>> time. >>>>>>>>>> Just a thought, anyway, >>>>>>>>>> >>>>>>>>>> Greg >>>>>>>>>> >>>>>>>>>> On 22 March 2017 at 13:47, Anthony Maire <maire.anth...@gmail.com > >>>>>>>>> wrote: >>>>>>>>>>> Hi >>>>>>>>>>> >>>>>>>>>>> We are currently using another logging framework in production, but >>>>>> I'm >>>>>>>>>>> pushing to change it for log4j2. >>>>>>>>>>> >>>>>>>>>>> One common issue we have with that framework (and I assume we can >>>>>> have >>>>>>>>> the >>>>>>>>>>> same with log4j2) is that all of our JVMs (we can have more than 50 >>>>>>>>> JVMs on >>>>>>>>>>> the same server in production) roll their file at midnight. >>>>>>>>>>> >>>>>>>>>>> When this happens, the system became often not usable for a few >>>>>> seconds >>>>>>>>>>> because of the simultaneous zipping of all the rolled files that >>>>>>>>> overload >>>>>>>>>>> the CPU (although zipping is done in a specific background thread). >>>>>> To >>>>>>>>>>> reduce this effect, we are combining a time based rolling policy >>>>>> with a >>>>>>>>>>> sized based policy to zip smaller files, but this is not enough to >>>>>> make >>>>>>>>> the >>>>>>>>>>> system fully responsive at midnight. >>>>>>>>>>> >>>>>>>>>>> A pretty cool feature for us to avoid this issue is to have the >>>>>>>>> possibility >>>>>>>>>>> when a rolling is triggered because of a time based policy to change >>>>>>>>> file >>>>>>>>>>> immediately, but to wait for a random amount of time (within a >>>>>>>>> configurable >>>>>>>>>>> limit) before starting the compression. This random delay should >>>>>> help a >>>>>>>>> lot >>>>>>>>>>> to avoid contention on CPU cycles. >>>>>>>>>>> >>>>>>>>>>> Does log4j2 have something to solve this kind of issue ? If not, >>>>>> would >>>>>>>>> you >>>>>>>>>>> accept a pull request for this (I will open a Jira if needed) ? >>>>>>>>>>> >>>>>>>>>>> Regards, >>>>>>>>>>> Anthony >>>>>>>>>>> >>>>>>>>> >>>>>>>>> ------------------------------------------------------------ --------- >>>>>>>>> To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org >>>>>>>>> For additional commands, e-mail: log4j-user-help@logging. apache.org >>>>>>>>> >>>>>>>>> >>>>>>> ------------------------------------------------------------ --------- >>>>>>> To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org >>>>>>> For additional commands, e-mail: log4j-user-h...@logging.apache.org >>>>>> --------------------------------------------------------------------- >>>>>> To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org >>>>>> For additional commands, e-mail: log4j-user-h...@logging.apache.org >>>>>> >>>>>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org >>> For additional commands, e-mail: log4j-user-h...@logging.apache.org >>> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org >> For additional commands, e-mail: log4j-user-h...@logging.apache.org >> > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org > For additional commands, e-mail: log4j-user-h...@logging.apache.org > --------------------------------------------------------------------- To unsubscribe, e-mail: log4j-user-unsubscr...@logging.apache.org For additional commands, e-mail: log4j-user-h...@logging.apache.org
