Ubuntu 16.04启动应用失败
系统版本如下：
```
$ lsb_release -a
LSB Version:	core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch
Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.4 LTS
Release:	16.04
Codename:	xenial
$ uname -a
Linux dev-test2 4.4.0-117-generic #141-Ubuntu SMP Tue Mar 13 11:58:07 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
```
启动报错如下：
```
> site-operation-system@1.0.0 dev:server /home/frontend/site-operation-system/server
> EGG_SERVER_ENV=dev npm run start


> site-operation-system@1.0.0 start /home/frontend/site-operation-system/server
> egg-scripts start --daemon --title=site-operation-system

[egg-scripts] Starting egg application at /home/frontend/site-operation-system/server
[egg-scripts] Run node /home/frontend/site-operation-system/server/node_modules/egg-scripts/lib/start-cluster {"title":"site-operation-system","baseDir":"/home/frontend/site-operation-system/server","framework":"/home/frontend/site-operation-system/server/node_modules/egg"} --title=site-operation-system
[egg-scripts] Save log file to /home/frontend/logs
[egg-scripts] Wait Start: 1...
[egg-scripts] Wait Start: 2...
[egg-scripts] Wait Start: 3...
[egg-scripts] Wait Start: 4...
[egg-scripts] tail -n 100 /home/frontend/logs/master-stderr.log
[egg-scripts] Got error when startup: 
[egg-scripts] (node:1713) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
[egg-scripts] (node:1718) DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to the MongoClient constructor.
[egg-scripts] (node:1713) DeprecationWarning: collection.ensureIndex is deprecated. Use createIndexes instead.
[egg-scripts] 
[egg-scripts] Start got error, see /home/frontend/logs/master-stderr.log
[egg-scripts] Or use `--ignore-stderr` to ignore stderr at startup.
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! site-operation-system@1.0.0 start: `egg-scripts start --daemon --title=site-operation-system`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the site-operation-system@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/frontend/.npm/_logs/2020-11-18T15_42_39_435Z-debug.log
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! site-operation-system@1.0.0 dev:server: `EGG_SERVER_ENV=dev npm run start`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the site-operation-system@1.0.0 dev:server script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/frontend/.npm/_logs/2020-11-18T15_42_39_453Z-debug.log
```  
比较奇怪的是，经常出现这样的问题，前面几次启动都失败，后面总有一次可以正常跑起来。以上是启动失败时的报错信息。