elasticsearch启动时报错：
Java HotSpot™ 64-Bit Server VM warning: INFO: os::commit_memory(0x00000000e5330000, 449642496, 0) failed; error=‘Cannot allocate memory’ (errno=12) There is insufficient memory for the Java Runtime Environment to continue. Native memory allocation (mmap) failed to map 449642496 bytes for committing reserved memory. An error report file with more information is saved as: /opt/elasticsearch/hs_err_pidxxx.log
原因：没有足够的内存供JRE运行
解决：修改es配置参数
vim config/jvm.options
修改JVM参数，将其改小即可：
-Xms512m -Xmx512m