im服务启动时报错 java version "1.8.0_441" Java(TM) SE Runtime Environment (build 1.8.0_441-b07) Java HotSpot(TM) 64-Bit Server VM (build 25.441-b07, mixed mode) 警告：没有设置JVM内存参数！ 请设置JVM参数Xmx和Xms，设置为您为IM服务预留的内存大小，注意需要刨除操作系统占用，如果有其它系统也需要相应去除占用。

Error: VM option 'UseG1GC' is experimental and must be enabled via -XX:+UnlockExperimentalVMOptions. Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit.