Wrapper for Java 8/9 $JAVA_HOME/bin/java for use in docker containers, where the JVM settings must adjusted to conform to cgroup memory limits.
Essentially, the issue with -XX:+UseCGroupMemoryLimitForHeap in Java 8u131+ is that it 1) doesn't account for Metaspace, and 2) in combination with
-XX:MaxRAMFraction, it is impossible to allocate a fraction between 0% and 50% of available memory to Metaspace.
This command rewrites the JVM memory setting arguments before being passed through to $JAVA_HOME/bin/java to make sure that a specific, or at least
minimum -XX:MaxMetaspaceSize is set, and that the -Xmx and -Xms are reduced, if necessary, such that MaxMetaspaceSize >= 64m,
MetaspaceSize <= MaxMetaspaceSize, InitialHeapSize <= MaxHeapSize, and MaxHeapSize + MaxMetaspaceSize <= CGroupMemLimit.
This command was ported from a bash script that is included along side for comparison.
jvshim is designed to be slipped into shell's PATH variable to intercept calls to java. When dispatching to the real java, it skips its own path
if found before the jvm.