README.md

java-perf-tests

Demos designed to show java metrics under stress and tuning conditions

build:

javac -d bin -s src/main/java `find src -name "*.java"`

Memory Performance

Enough RAM

java -cp bin -Xmx128m -XX:+UseParallelGC com.jrandrews.jsc.perf.Main
java -cp bin -Xmx128m -XX:+UseG1GC com.jrandrews.jsc.perf.Main

Not quite enough RAM

java -cp bin -Xmx50m -XX:+UseParallelGC -XX:FlightRecorderOptions=stackdepth=128 com.jrandrews.jsc.perf.Main
java -cp bin -Xmx50m -XX:+UseG1GC       com.jrandrews.jsc.perf.Main

Overhead from JFR might require and extra 1m of heap if you want to make recordings in addition to monitoring JMX.

Leak

java -cp bin -Xmx128m -XX:+UseG1GC       com.jrandrews.jsc.perf.Main leak
java -cp bin -Xmx128m -XX:+UseParallelGC com.jrandrews.jsc.perf.Main leak

add

-XX:FlightRecorderOptions=stackdepth=128

to avoid JFR complaints if you want to observe these JVMs with JDK Flight Control and JFR.

GC logging:

JDK 8

LOGS="-Xloggc:gc.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=10M"
LOGS="${LOGS} -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintReferenceGC"
LOGS="${LOGS} -XX:+PrintTenuringDistribution -XX:+PrintGCApplicationStoppedTime"

example:

java -cp bin -Xmx128m ${LOGS} -XX:+UseG1GC       com.jrandrews.jsc.perf.Main leak

JDK >= 9

LOGS="-Xlog:gc*,gc+ref=debug,gc+age=trace,gc+heap=debug:file=gc%p%t.log:tags,uptime,time:filecount=10,filesize=10m"

example:

java -cp bin -Xmx128m ${LOGS} -XX:+UseG1GC       com.jrandrews.jsc.perf.Main leak

Deadlock

java -cp bin com.jrandrews.jsc.perf.Deadlock

Thread contention

java -cp bin com.jrandrews.jsc.perf.ThreadContention