ElasticSearch启动报错,报ERROR: [3] bootstrap checks failed

新装es启动时，会遇到以下错误情况：

ERROR: [3] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]
解决办法：
编辑 /etc/security/limits.conf，追加以下内容；
* soft nofile 65536
* hard nofile 65536
此文件修改后需要重新登录用户，才会生效
[2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
解决办法：
编辑 /etc/sysctl.conf，追加以下内容：
vm.max_map_count=655360
保存后，执行：

sysctl -p

[3]: max number of threads [2048] for user [tongtech] is too low, increase to at least [4096]
错误原因：启动检查未通过
    elasticsearch用户的最大线程数太低
解决办法：
vim /etc/security/limits.d/90-nproc.conf
将2048改为4096或更大