elasticsearch启动常见错误

报错详情

[2020-03-15T21:17:37,703][INFO ][o.e.b.BootstrapChecks    ] [2wYIoJn] bound or publishing to a non-loopback address, enforcing bootstrap checks
ERROR: [3] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]
[2]: max of threads [3818] for user [ucode] is too low, increase to at least [4096]
[3]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
[2020-03-15T21:17:37,800][INFO ][o.e.n.Node               ] [2wYIoJn] stopping ...
[2020-03-15T21:17:37,829][INFO ][o.e.n.Node               ] [2wYIoJn] stopped
[2020-03-15T21:17:37,830][INFO ][o.e.n.Node               ] [2wYIoJn] closing ...
[2020-03-15T21:17:37,847][INFO ][o.e.n.Node               ] [2wYIoJn] closed
[2020-03-15T21:17:37,852][INFO ][o.e.x.m.j.p.NativeController] Native controller process has stopped - no new native processes can be started
^C
[1]+  Exit 78

nohup /home/ucode/program/software/elk/elasticsearch-6.3.1/bin/elasticsearch > elasticsearch.out 2>&1

问题出现环境，OS版本：CentOS-7-x86_64-Minimal-1708；ES版本：elasticsearch-6.2.2。

1、max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]

　　每个进程最大同时打开文件数太小，可通过下面2个命令查看当前数量

ulimit -Hn
ulimit -Sn

　　修改/etc/security/limits.conf文件，增加配置，用户退出后重新登录生效

*               soft    nofile          65536
*               hard    nofile          65536

2、max number of threads [3818] for user [es] is too low, increase to at least [4096]

　　问题同上，最大线程个数太低。修改配置文件/etc/security/limits.conf（和问题1是一个文件），增加配置

*               soft    nproc           4096
*               hard    nproc           4096

　　可通过命令查看

ulimit -Hu
ulimit -Su

修改后的文件：

3、max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

　　修改/etc/sysctl.conf文件，增加配置vm.max_map_count=262144

vi /etc/sysctl.conf
sysctl -p

　　执行命令sysctl -p生效

4、Exception in thread "main" java.nio.file.AccessDeniedException: /usr/local/elasticsearch/elasticsearch-6.2.2-1/config/jvm.options

　　elasticsearch用户没有该文件夹的权限，执行命令

chown -R es:es /usr/local/elasticsearch/