Re: [infinispan-dev] if (trace) logger.tracef - it makes sense

this discussion appears on this mailing list approximately every 2 years :) On 30 September 2016 at 13:41, Dan Berindei <dan.berindei(a)gmail.com&gt; wrote: > I should stress that we only cache `isTraceEnabled()` in a static > field. Debug logging can still be enabled or disabled on the fly. > > > Cheers > Dan > > > On Fri, Sep 30, 2016 at 3:14 PM, Wolf Fink <wfink(a)redhat.com&gt; wrote: >> Ok, >> >> thanks for clarifying it. >> >> So there is a factor of 3 for the test if no trace is enabled, just for >> checking. >> It makes sense to use it. >> But my concern is still that it is sometimes good to have the possibility to >> enable debug for some important information in production just on the fly >> and switch it of to prevent from throtteling the server by that log >> statements or restart the server. >> We have the same issue in EAP but here a restart is not that bad as here you >> don't have to load the cache or rebalance the cluster for stop/start. >> >> - Wolf >> >> On Fri, Sep 30, 2016 at 1:53 PM, David M. Lloyd <david.lloyd(a)redhat.com&gt; >> wrote: >>> >>> On 09/30/2016 01:53 AM, Sebastian Laskawiec wrote: >>>> Hey! >>>> >>>> A while ago I asked Radim and Dan about these kind of constructs [1]: >>>> >>>> private boolean trace = logger.isTraceEnabled(); //stored in a field >>>> >>>> ... called in some method ... >>>> if(trace) >>>> logger.tracef(...); >>>> ... >>>> >>>> At first they seemed wrong to me, because if one changes logging level >>>> (using JMX for example), the code won't notice it. I also though it's >>>> quite ok to use tracef directly, because JIT will inline and optimize >>>> it. >>>> >>>> Unfortunately my benchmarks [2] show that I was wrong. Logger#tracef >>>> indeed checks if the logging level is enabled but since JBoss Logging >>>> may use different backends, the check is not trivial and is not inlined >>>> (at least with default settings). >>> >>> What backend where you using with your test? >>> >>>> The performance results look like this: >>>> Benchmark Mode Cnt Score Error >>>> Units >>>> MyBenchmark.noVariable thrpt 20 *717252060.124* ± 13420522.229 >>>> ops/s >>>> MyBenchmark.withVariable thrpt 20 *2358360244.627* ± 50214969.572 >>>> ops/s >>>> >>>> So if you even see a construct like this: logger.debuf or logger.tracef >>>> - make sure you check if the logging level is enabled (and the check >>>> result is stored in a field). >>>> >>>> That was a bit surprising and interesting lesson :D >>>> >>>> Thanks >>>> Sebastian >>>> >>>> [1] >>>> https://github.com/infinispan/infinispan/pull/4538#discussion_r80666086 >>>> [2] https://github.com/slaskawi/jboss-logging-perf-test >>>> >>>> >>>> _______________________________________________ >>>> infinispan-dev mailing list >>>> infinispan-dev(a)lists.jboss.org >>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >>>> >>> >>> -- >>> - DML >>> _______________________________________________ >>> infinispan-dev mailing list >>> infinispan-dev(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev > > _______________________________________________ > infinispan-dev mailing list > infinispan-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/infinispan-dev _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev