发现问题：
启动 node 项目ReactNative时候出现报错Error: ENOSPC: no space left on device, watch
[root@iz2zeihk6kfcls5kwmqzj1z JFReactNativeProject]# npm start
> wk_rn@0.0.1 start /app/jenkins_workspace/workspace/JFReactNativeProject
> react-native start
┌──────────────────────────────────────────────────────────────────────────────┐
│ │
│ Running Metro Bundler on port 8081. │
│ │
│ Keep Metro running while developing on any JS projects. Feel free to │
│ close this tab and run your own Metro instance if you prefer. │
│ │
│ https://github.com/facebook/react-native │
│ │
└──────────────────────────────────────────────────────────────────────────────┘
Looking for JS files in
/app/jenkins_workspace/workspace/JFReactNativeProject
Loading dependency graph...fs.js:1413
throw error;
^
Error: ENOSPC: no space left on device, watch '/app/jenkins_workspace/workspace/JFReactNativeProject/node_modules/.staging/react-native-ddd311e5/ReactAndroid/src/androidTest/java/com/facebook/react/testing/idledetection'
at FSWatcher.start (fs.js:1407:26)
at Object.fs.watch (fs.js:1444:11)
at NodeWatcher.watchdir (/app/jenkins_workspace/workspace/JFReactNativeProject/node_modules/_sane@4.1.0@sane/src/node_watcher.js:159:22)
at Walker.<anonymous> (/app/jenkins_workspace/workspace/JFReactNativeProject/node_modules/_sane@4.1.0@sane/src/common.js:109:31)
at Walker.emit (events.js:182:13)
at /app/jenkins_workspace/workspace/JFReactNativeProject/node_modules/_walker@1.0.7@walker/lib/walker.js:69:16
at go$readdir$cb (/app/jenkins_workspace/workspace/JFReactNativeProject/node_modules/_graceful-fs@4.2.2@graceful-fs/graceful-fs.js:187:14)
at FSReqWrap.oncomplete (fs.js:169:20)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! wk_rn@0.0.1 start: `react-native start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the wk_rn@0.0.1 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! /root/.npm/_logs/2019-09-25T06_57_58_754Z-debug.log
解决办法：
ENOSPC的含义是 Error No more hard-disk space available（没有更多的磁盘空间可以使用）
首先使用df -hT发现磁盘空间还有很多
然后从报错日志中发现FSWatcher和Object.fs.watch字段，然后查看系统允许用户监听文件数相关内容
#表示同一用户同时可以添加的watch数目（watch一般是针对目录，决定了同时同一用户可以监控的目录数量）
[root@iz2zeihk6kfcls5kwmqzj1z JFReactNativeProject]# cat /proc/sys/fs/inotify/max_user_watches
8192
[root@iz2zeihk6kfcls5kwmqzj1z JFReactNativeProject]# echo 100000 > /proc/sys/fs/inotify/max_user_watches
[root@iz2zeihk6kfcls5kwmqzj1z JFReactNativeProject]# cat /proc/sys/fs/inotify/max_user_watches
100000
永久生效方法如下：（建议采用此方法）
vim /etc/sysctl.conf
fs.inotify.max_user_watches = 100000（后面值根据实际情况可自行调整）
添加并运行/sbin/sysctl -p即可
启动验证：
再次启动，正常
[root@iz2zeihk6kfcls5kwmqzj1z JFReactNativeProject]# npm start
> wk_rn@0.0.1 start /app/jenkins_workspace/workspace/JFReactNativeProject
> react-native start
┌──────────────────────────────────────────────────────────────────────────────┐
│ │
│ Running Metro Bundler on port 8081. │
│ │
│ Keep Metro running while developing on any JS projects. Feel free to │
│ close this tab and run your own Metro instance if you prefer. │
│ │
│ https://github.com/facebook/react-native │
│ │
└──────────────────────────────────────────────────────────────────────────────┘
Looking for JS files in
/app/jenkins_workspace/workspace/JFReactNativeProject
Loading dependency graph, done.
知识点：
inotify 的默认内核参数
/proc/sys/fs/inotify/max_queued_events默认值:16384该文件中的值为调用inotify_init时分配给inotify instance中可排队的event的数目的最大值，超出这个值得事件被丢弃，但会触发IN_Q_OVERFLOW事件/proc/sys/fs/inotify/max_user_instances默认值:128指定了每一个real user ID可创建的inotify instatnces的数量上限/proc/sys/fs/inotify/max_user_watches默认值:8192指定了每个inotify instance相关联的watches的上限
注意: max_queued_events 是 Inotify 管理的队列的最大长度，文件系统变化越频繁，这个值就应该越大
如果你在日志中看到Event Queue Overflow，说明 max_queued_events 太小需要调整参数后再次使用.