故障：autovacuum和stats collector进程未正常启动

PostgreSQL数据库启动时，发现日志中有如下提示信息：

2020-12-02 10:42:15.966 CST,,,3645,,5fc6ff07.e3d,2,,2020-12-02 10:42:15 CST,,0,LOG,XX000,"could no
t bind socket for statistics collector: Cannot assign requested address",,,,,,,,,""
2020-12-02 10:42:15.966 CST,,,3645,,5fc6ff07.e3d,3,,2020-12-02 10:42:15 CST,,0,LOG,00000,"disablin
g statistics collector for lack of working socket",,,,,,,,,""

查看后台进程，发现autovacuum launcher和stats collector进程未正常启动。

$ ps f -u postgres
3645 ?        Ss     0:00 /opt/pg124/bin/postgres -D /opt/data6000
 3646 ?        Ss     0:00  \_ postgres: logger   
 3648 ?        Ss     0:00  \_ postgres: checkpointer   
 3649 ?        Ss     0:00  \_ postgres: background writer   
 3650 ?        Ss     0:00  \_ postgres: walwriter   
 3651 ?        Ss     0:00  \_ postgres: logical replication launcher  

因为autovacuum launcher process和stats collector process进程需要通过本地回环接口收集统计信息，如果本地回环接口down掉，或者/etc/hosts配置有问题，则那两个进程会启动失败。

本文本地回环接口服务正常，但/etc/hosts配置文件有错误，修改localhost时有拼写错误。

预防措施：
1.检查本地回环接口是否正常
2.psql使用localhost检查联通性