Native controller process has stopped - no new native processes can be started

昨天安装好，今天启动Elasticsearch时失败：

...
ERROR: [1] bootstrap checks failed
[1]: max number of threads [2048] for user [vagrant] is too low, increase to at least [4096]
[2]: the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured
[2019-11-15T14:46:51,596][INFO ][o.e.n.Node               ] [machine2] stopping ...
[2019-11-15T14:46:51,640][INFO ][o.e.n.Node               ] [machine2] stopped
[2019-11-15T14:46:51,640][INFO ][o.e.n.Node               ] [machine2] closing ...
[2019-11-15T14:46:51,666][INFO ][o.e.n.Node               ] [machine2] closed
[2019-11-15T14:46:51,669][INFO ][o.e.x.m.p.NativeController] [machine2] Native controller process has stopped - no new native processes can be started

遇到这样的错误，不能看最后一句话。看前面的error，这里有两个错误。

第一个解决方案可以看这里给出了两种方法：

  1. 使用Linux命令ulimit -u xxxx设置。
  2. 修改/etc/security/limits.conf中对应当前用户的nproc值

额外说下，nproc代表max number of processes。这在文件前面有解释

第二个问题看这里，可以知道，没有做任何网络配置，Elasticsearch会绑定在loopback address(127.0.0.1)上，并扫描9300到9305的端口去尝试连接其他节点（这样做是方便了集群）。出现这个问题是因为昨天我将IP地址修改了。所以，解决这个问题可以：

  1. 将昨天的改动去掉，网络配置的IP地址恢复默认配置
  2. 在$ES_HOME/config/elasticsearch.yml的Discovery模块中配置discovery.seed_hosts: []