在将超级管理员和普通用户添加到MongoDB之后，我尝试重新启动，但是失败了。它显示了一个非常奇怪的问题：
[root@VM_0_11_centos /]# service mongod restart
Redirecting to /bin/systemctl restart mongod.service
Job for mongod.service failed because the control process exited with error code. See "systemctl status mongod.service" and "journalctl -xe" for details.
当我尝试重新输入mongodb时，连接失败：
[root@VM_0_11_centos /]# mongo
MongoDB shell version v3.4.20
connecting to: mongodb://127.0.0.1:27017
2019-06-02T12:04:03.103+0800 W NETWORK [thread1] Failed to connect to 127.0.0.1:27017, in(checking socket for error after poll), reason: Connection refused
2019-06-02T12:04:03.103+0800 E QUERY [thread1] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed :
connect@src/mongo/shell/mongo.js:240:13
@(connect):1:6
exception: connect failed
这是mongo的日志：
2019-06-02T11:57:55.908+0800 I COMMAND [conn2] command admin.system.version appName: "MongoDB Shell" command: createUser { createUser: "root", pwd: "xxx", roles: [ { role: "root", db: "admin" } ], digestPassword: false, writeConcern: { w: "majority", wtimeout: 600000.0 } } numYields:0 reslen:22 locks:{ Global: { acquireCount: { r: 6, w: 4 } }, Database: { acquireCount: { r: 1, W: 4 } }, Collection: { acquireCount: { r: 1, w: 3 } } } protocol:op_command 201ms
2019-06-02T12:00:56.119+0800 I - [conn2] end connection 127.0.0.1:46604 (1 connection now open)
2019-06-02T12:02:13.168+0800 I CONTROL [signalProcessingThread] got signal 15 (Terminated), will terminate after current cmd ends
2019-06-02T12:02:13.168+0800 I NETWORK [signalProcessingThread] shutdown: going to close listening sockets...
2019-06-02T12:02:13.168+0800 I NETWORK [signalProcessingThread] closing listening socket: 7
2019-06-02T12:02:13.168+0800 I NETWORK [signalProcessingThread] closing listening socket: 8
2019-06-02T12:02:13.168+0800 I NETWORK [signalProcessingThread] removing socket file: /tmp/mongodb-27017.sock
2019-06-02T12:02:13.168+0800 I NETWORK [signalProcessingThread] shutdown: going to flush diaglog...
2019-06-02T12:02:13.168+0800 I FTDC [signalProcessingThread] Shutting down full-time diagnostic data capture
2019-06-02T12:02:13.170+0800 I STORAGE [signalProcessingThread] WiredTigerKVEngine shutting down
2019-06-02T12:02:13.456+0800 I STORAGE [signalProcessingThread] shutdown: removing fs lock...
2019-06-02T12:02:13.456+0800 I CONTROL [signalProcessingThread] now exiting
2019-06-02T12:02:13.456+0800 I CONTROL [signalProcessingThread] shutting down with code:0
可以帮我吗？