#################
#  GC SETTINGS  #
#################
### G1 Settings (experimental, comment previous section and uncomment section below to enable)

## Use the Hotspot garbage-first collector.
-XX:+UseG1GC
#
## Have the JVM do less remembered set work during STW, instead
## preferring concurrent GC. Reduces p99.9 latency.
-XX:G1RSetUpdatingPauseTimePercent=5
#
## Main G1GC tunable: lowering the pause target will lower throughput and vise versa.
## 200ms is the JVM default and lowest viable setting
## 1000ms increases throughput. Keep it smaller than the timeouts in cassandra.yaml.
-XX:MaxGCPauseMillis=15000

## Optional G1 Settings

# Save CPU time on large (>= 16GB) heaps by delaying region scanning
# until the heap is 70% full. The default in Hotspot 8u40 is 40%.
-XX:InitiatingHeapOccupancyPercent=30
# For systems with > 8 cores, the default ParallelGCThreads is 5/8 the number of logical cores.
# Otherwise equal to the number of cores when 8 or less.
# Machines with > 10 cores should try setting these to <= full cores.
-XX:ParallelGCThreads=8
# By default, ConcGCThreads is 1/4 of ParallelGCThreads.
# Setting both to the same value can reduce STW durations.
-XX:ConcGCThreads=8

### GC logging options -- uncomment to enable

-XX:+PrintGCDetails
-XX:+PrintGCDateStamps
-XX:+PrintHeapAtGC
-XX:+PrintTenuringDistribution
-XX:+PrintGCApplicationStoppedTime
-XX:+PrintPromotionFailure
-XX:PrintFLSStatistics=1
-Xloggc:/var/log/cassandra/gc.log
-XX:+UseGCLogFileRotation
-XX:NumberOfGCLogFiles=10
-XX:GCLogFileSize=10M


# Experimental options to increase Eden size to solve problem with GC
-XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=40 -XX:G1MaxNewSizePercent=60