rocketmq - 内存不足

环境是linux
1、http://rocketmq.apache.org/docs/quick-start/ 按照官网来启动mqnamesrv和mqbroker报错 
错误如下 
There is insufficient memory for the Java Runtime Environment to continue.

There is insufficient memory for the Java Runtime Environment to continue.  
Native memory allocation (mmap) failed to map 8589934592 bytes for committing reserved memory.  
Possible reasons:  
The system is out of physical RAM or swap space  
In 32 bit mode, the process size limit was hit  
Possible solutions:  
Reduce memory load on the system  
Increase physical memory or swap space  
Check if swap backing store is full  
Use 64 bit Java on a 64 bit OS  
Decrease Java heap size (-Xmx/-Xms)  
Decrease number of Java threads  
Decrease Java thread stack sizes (-Xss)  
Set larger code cache with -XX:ReservedCodeCacheSize=  
This output file may be truncated or incomplete.

Out of Memory Error (os_linux.cpp:2640), pid=2428, tid=0x00007fada5259700

JRE version: (8.0_172-b11) (build )  
Java VM: Java HotSpot(TM) 64-Bit Server VM (25.172-b11 mixed mode linux-amd64 compressed oops) 
Java运行时环境的内存不足，无法继续，本机内存分配（mmap）未能映射8589934592字节，用于提交保留内存 
解决办法，找到runserver.sh和runbroker.sh，编辑 

#JAVA_OPT="${JAVA_OPT} -server -Xms8g -Xmx8g -Xmn4g" (默认需要内存空间)

JAVA_OPT=”${JAVA_OPT} -server -Xms256m -Xmx256m -Xmn125m -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m” 
改成如上就可以了