Notes waiting for Triage

Java heap dump setup path

https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/clopts001.html#:~:text=By default the heap dump,-XX%3AHeapDumpPath%3D option.

KAFKA_HEAP_OPTS+=" -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/data/kafka_heapdump.hprof"
KAFKA_HEAP_OPTS+=" -XX:+ExitOnOutOfMemoryError -XX:ErrorFile=/data/kafka_error.log"

Random Regex help 🎱

MyEngine\\..[0-9a-zA-Z._-]*.hello(\\.world)?

• Matches MyEngine.something.something.hello.world and MyEngine.ckjekrjek.kjekjre.hello

Java Articles

• https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-November/070782.html
• https://docs.oracle.com/en/java/javase/11/gctuning/garbage-first-garbage-collector-tuning.html#GUID-90E30ACA-8040-432E-B3A0-1E0440AB556A
• https://docs.oracle.com/en/java/javase/11/gctuning/garbage-first-garbage-collector-tuning.html#GUID-0770AB01-E334-4E23-B307-FD2114B16E0E
• Facebook evaluating and using GraalVM: https://medium.com/graalvm/graalvm-at-facebook-af09338ac519

Managing versions

jenv is much more useful than sdkman.

https://sdkman.io/ - Switching jdks. Another good option and more preferable is jenv - you can download different jvms and then link to jenv and switch to them manually - many things are unavailable with sdkman

# also an option
export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)
export JAVA_14_HOME=$(/usr/libexec/java_home -v14)
export JAVA_11_HOME=$(/usr/libexec/java_home -v11)

alias java8='export JAVA_HOME=$JAVA_8_HOME'
alias java14='export JAVA_HOME=$JAVA_14_HOME'
alias java11='export JAVA_HOME=$JAVA_11_HOME'