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dacr/jvm.md

Last active April 2, 2023 10:13
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jvm cheat sheet / published by https://github.com/dacr/code-examples-manager #12adcc40-b47b-48dc-9ca6-f4f3ba3df9d8/6e877c962827e60f7dd6ebf17a2e2f2cd3ed07de
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jvm.md

JVM cheat sheets

settings and chosen defaults

java -XshowSettings -version
java -XshowSettings:vm --version

Live monitoring

jps
jstack -e -l 7 > jstack-$(date -u +"%Y-%m-%dT%H:%M:%SZ")
jstat -gc 7 2000

flags with default values

java -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version

Memory

Use showSettings:vm to display JVM decisions :

java -XshowSettings:vm -version
java -Xms1500m -Xmx1600m -XshowSettings:vm -version
java -XX:MinRAMPercentage=50.0 -XX:MaxRAMPercentage=85.0 -XshowSettings:vm -version

Dump/stats mémoire :

jmap -histo 7
jmap -dump:live,format=b,file=heap.bin 7

garbage gc monitoring

JVM <=8

java -verbose:gc -XX:+PrintGC -XX:+PrintGCDetails

JVM >8

java -Xlog:gc*
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