We went through an exercise of setting things up so that DEBUG logging was asynchronous would give people a “production” debug log. https://issues.apache.org/jira/browse/CASSANDRA-10241 If there are some things going out at DEBUG that cause performance issues then most likely those should be moved to TRACE so that debug logging can stay enabled for all the useful information found there.
-Jeremiah > On Mar 17, 2018, at 1:49 PM, Alexander Dejanovski <a...@thelastpickle.com> > wrote: > > Hi folks, > > we've been upgrading clusters from 2.0 to 2.2 recently and we've noticed > that debug logging was causing serious performance issues in some cases, > specifically because of its use in the query pager. > > I've opened a ticket with some benchmarks and flame graphs : > https://issues.apache.org/jira/browse/CASSANDRA-14318 > > The problem should be less serious in the read path with Cassandra 3.0 and > above as the query pager code has been reworked and doesn't log at debug > level. > I think that debug logging shouldn't be turned on by default though, since > we see it doesn't come for free and that it lowers read performance in 2.2. > > Was there any specific reason why it was enabled by default in 2.2 ? > > Is anyone opposed to disabling debug logging by default in all branches ? > > -- > ----------------- > Alexander Dejanovski > France > @alexanderdeja > > Consultant > Apache Cassandra Consulting > http://www.thelastpickle.com
