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svanoort / gcsettings.sh
Last active December 20, 2023 02:27
Blessed GC settings for big servers
# Base settings and GC logging
-server -XX:+AlwaysPreTouch # First should be default, but we make it explicit, second pre-zeroes memory mapped pages on JVM startup -- improves runtime performance
# -Xloggc:gc-%t.log # CUSTOMIZE LOCATION HERE - $path/gc-%t.log -- the %t in the gc log file path is so we get a new file with each JVM restart
-XX:NumberOfGCLogFiles=5 -XX:+UseGCLogFileRotation -XX:GCLogFileSize=20m # Limits the number of files, logs to folder
-XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintGCCause
-XX:+PrintTenuringDistribution -XX:+PrintReferenceGC -XX:+PrintAdaptiveSizePolicy # gather info on object age & reference GC time for further tuning if needed.
# G1 specific settings -- probably should be default for multi-core systems with >2 GB of heap (below that, default is probably fine)
-XX:+UseG1GC
-XX:+UseStringDeduplication