New OpenJDK setting for better memory allocation.

Since -XX:InitialRAMFraction, -XX:MaxRAMFraction, and -XX:MinRAMFraction have been deprecated. Now we changed to

• -XX:InitialRAMPercentage
• -XX:MaxRAMPercentage
• -XX:MinRAMPercentage

Example:

$ java -version
openjdk version "1.8.0_252"
OpenJDK Runtime Environment Corretto-8.252.09.1 (build 1.8.0_252-b09)
OpenJDK 64-Bit Server VM Corretto-8.252.09.1 (build 25.252-b09, mixed mode)
$ free -m
              total        used        free      shared  buff/cache   available
Mem:           3921         462         851           6        2608        3170
Swap:          4091          10        4081
$ java -XX:+PrintFlagsFinal  -XX:MaxRAMPercentage=10.0 -version  2>&1 | grep MaxHeapSize
    uintx MaxHeapSize                              := 413138944                           {product}
$ java -XX:+PrintFlagsFinal  -XX:MaxRAMPercentage=50.0 -version  2>&1 | grep MaxHeapSize
    uintx MaxHeapSize                              := 2057306112                          {product}
$ java -XX:+PrintFlagsFinal  -XX:MaxRAMPercentage=100.0 -version  2>&1 | grep MaxHeapSize
    uintx MaxHeapSize                              := 4112515072                          {product}

Use MaxRAMPercentage=100.0 is such a bad idea , need a free space for NoneHeap too.

Example:

Deployment

containers:
      - env:
        - name: JAVA_OPTS
          value: -XX:InitialRAMPercentage=80.0 -XX:MaxRAMPercentage=80.0 -XX:MinRAMPercentage=80.0
        image: tomcat:8-jdk8-corretto
        imagePullPolicy: IfNotPresent
        name: tomcat
        resources:
          limits:
            memory: 1000Mi

Note:

NGCMX: Maximum new generation capacity (kB).
OGCMX: Maximum old generation capacity (kB).