Unable to use other JVM memory options to control zookeeper memory usage.

After upgrading from version 3.4.14 to version 3.6.4, it was found that other JVM memory options such as - XX: MaxRAMPercentage cannot be used to control the memory usage of zookeeper. Upon investigation, it was found that the reason was due to the addition of a default setting for heap size in the zkEnv.sh script in version 3.5, with a default value of 1000M.

ZK_SERVER_HEAP="${ZK_SERVER_HEAP:-1000}"
export SERVER_JVMFLAGS="-Xmx${ZK_SERVER_HEAP}m $SERVER_JVMFLAGS"

When the user uses - XX: MaxRAMPercentage to control the memory usage of zookeeper, it is found that the memory configuration will be overwritten by the default - Xmx configuration value. This does not meet the memory usage configuration required by the user.

In ZOOKEEPER-4391, it is also proposed to add a flag to disable the memory configuration behavior by default. This default value can only be optionally released when users need to use the default heap size configuration.