系统 centOS
首先进入服务器查看本地能否链接
由于是用pm2管理 pm2 list 列出所有用 PM2 启动的项目
pm2 logs 显示所有进程日志
0|www | 数据库链接失败 0|www | Error: connect ECONNREFUSED 127.0.0.1:3306 0|www | at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1161:14) 0|www | -------------------- 0|www | at Protocol._enqueue (/home/node/markdownserver/node_modules/mysql/lib/protocol/Protocol.js:145:48) 0|www | at Protocol.handshake (/home/node/markdownserver/node_modules/mysql/lib/protocol/Protocol.js:52:23) 0|www | at Connection.connect (/home/node/markdownserver/node_modules/mysql/lib/Connection.js:130:18) 0|www | at Object.query (/home/node/markdownserver/database/db.js:8:20) 0|www | at /home/node/markdownserver/routes/index.js:14:5 0|www | at Layer.handle [as handle_request] (/home/node/markdownserver/node_modules/express/lib/router/layer.js:95:5) 0|www | at next (/home/node/markdownserver/node_modules/express/lib/router/route.js:137:13) 0|www | at Route.dispatch (/home/node/markdownserver/node_modules/express/lib/router/route.js:112:3) 0|www | at Layer.handle [as handle_request] (/home/node/markdownserver/node_modules/express/lib/router/layer.js:95:5) 0|www | at /home/node/markdownserver/node_modules/express/lib/router/index.js:281:22 PM2 | App [www] with id [0] and pid [27584], exited with code [1] via signal [SIGINT] PM2 | Starting execution sequence in -fork mode- for app name:www id:0 PM2 | App name:www id:0 online
数据库挂了，查看数据库日志 查看数据库日志文件地址 cat /etc/my.cnf
tail -f /var/log/mysqld.log
2018-11-27T07:56:54.106090Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-11-27T07:56:54.108089Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.20) starting as process 30517 ...
2018-11-27T07:56:54.120484Z 0 [Note] InnoDB: PUNCH HOLE support available
2018-11-27T07:56:54.120538Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-11-27T07:56:54.120544Z 0 [Note] InnoDB: Uses event mutexes
2018-11-27T07:56:54.120548Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2018-11-27T07:56:54.120552Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-11-27T07:56:54.120558Z 0 [Note] InnoDB: Using Linux native AIO
2018-11-27T07:56:54.134609Z 0 [Note] InnoDB: Number of pools: 1
2018-11-27T07:56:54.134751Z 0 [Note] InnoDB: Using CPU crc32 instructions
2018-11-27T07:56:54.237143Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2018-11-27T07:56:54.237219Z 0 [ERROR] InnoDB: mmap(137428992 bytes) failed; errno 12
2018-11-27T07:56:54.237230Z 0 [ERROR] InnoDB: Cannot allocate memory for the buffer pool
2018-11-27T07:56:54.237237Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
2018-11-27T07:56:54.237248Z 0 [ERROR] Plugin 'InnoDB' init function returned error.
2018-11-27T07:56:54.237254Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2018-11-27T07:56:54.237261Z 0 [ERROR] Failed to initialize plugins.
2018-11-27T07:56:54.237265Z 0 [ERROR] Aborting
2018-11-27T07:56:54.237288Z 0 [Note] Binlog end
2018-11-27T07:56:54.436650Z 0 [Note] Shutting down plugin 'CSV'
2018-11-27T07:56:54.436951Z 0 [Note] /usr/sbin/mysqld: Shutdown complete
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
仔细阅读内容，有一句 Cannot allocate memory for the buffer pool 指明挂掉原因，内存不足 查看内存使用 free -m total used free shared buff/cache available Mem: 992 781 77 18 133 53 Swap: 0 0 0
只剩77MB内存了
重启服务器，重启相关服务