GC Logs are a weird science. I use a couple of resources to get through them. Regarding your question my 1.8.0_40 always have the first the "->". I "greped" through 2h of logs, and on a test environment.
I use the following set of options: -XX:+PrintGCDetails" -XX:+PrintGCDateStamps" -XX:+PrintHeapAtGC" -XX:+PrintTenuringDistribution" -XX:+PrintGCApplicationStoppedTime" -XX:+PrintPromotionFailure" -XX:PrintFLSStatistics=1" I don't know if the following could help but I use this tool to visualize my GC behaviour: https://github.com/chewiebug/GCViewer If I need insight into the GC as it goes I use Java VisualVM. Regards, Carlos Juzarte Rolo Cassandra Consultant Pythian - Love your data rolo@pythian | Twitter: cjrolo | Linkedin: *linkedin.com/in/carlosjuzarterolo <http://linkedin.com/in/carlosjuzarterolo>* Mobile: +31 6 159 61 814 | Tel: +1 613 565 8696 x1649 www.pythian.com On Tue, Jun 2, 2015 at 9:17 AM, Michał Łowicki <mlowi...@gmail.com> wrote: > > > On Tue, Jun 2, 2015 at 9:06 AM, Sebastian Martinka < > sebastian.marti...@mercateo.com> wrote: > >> this should help you: >> >> https://blogs.oracle.com/poonam/entry/understanding_cms_gc_logs >> > > I don't see there such format. Passed options related to GC are: > > -XX:+PrintGCDateStamps -Xloggc:/var/log/cassandra/gc.log > > >> >> >> Best Regards, >> Sebastian Martinka >> >> >> >> *Von:* Michał Łowicki [mailto:mlowi...@gmail.com] >> *Gesendet:* Montag, 1. Juni 2015 11:47 >> *An:* user@cassandra.apache.org >> *Betreff:* How to interpret some GC logs >> >> >> >> Hi, >> >> >> >> Normally I get logs like: >> >> >> >> 2015-06-01T09:19:50.610+0000: 4736.314: [GC 6505591K->4895804K(8178944K), >> 0.0494560 secs] >> >> >> >> which is fine and understandable but occasionalIy I see something like: >> >> 2015-06-01T09:19:50.661+0000: 4736.365: [GC 4901600K(8178944K), 0.0049600 >> secs] >> >> How to interpret it? Does it miss only part before "->" so memory >> occupied before GC cycle? >> >> -- >> >> BR, >> Michał Łowicki >> > > > > -- > BR, > Michał Łowicki > -- --
