Mongodb数据库异常 之 报错 Too many open files的问题解析

在项目实际使用过程中，客户反馈能打开网页但无法登陆，第一时间感觉到应该是数据库服务器挂了，于是查看Mongodb数据库服务器日志，果不其然挂了。
报错信息如下：

2020-12-28T13:21:21.731+0800 E STORAGE  [conn2624] WiredTiger error (24) [1609132881:731422][23581:0x7fe157189700], WT_SESSION.create: __posix_directory_sync, 135: /data1/mongodb/data/db/: directory-sync: open: Too many open files Raw: [1609132881:731422][23581:0x7fe157189700], WT_SESSION.create: __posix_directory_sync, 135: /data1/mongodb/data/db/: directory-sync: open: Too many open files
2020-12-28T13:21:21.731+0800 E STORAGE  [conn2624] WiredTiger error (24) [1609132881:731616][23581:0x7fe157189700], WT_SESSION.create: __posix_directory_sync, 151: /data1/mongodb/data/db/collection-1063-1706476241051221735.wt: directory-sync: Too many open files Raw: [1609132881:731616][23581:0x7fe157189700], WT_SESSION.create: __posix_directory_sync, 151: /data1/mongodb/data/db/collection-1063-1706476241051221735.wt: directory-sync: Too many open files
2020-12-28T13:21:21.731+0800 E STORAGE  [conn2624] WiredTiger error (-31804) [1609132881:731651][23581:0x7fe157189700], WT_SESSION.create: __wt_panic, 494: the process must exit and restart: WT_PANIC: WiredTiger library panic Raw: [1609132881:731651][23581:0x7fe157189700], WT_SESSION.create: __wt_panic, 494: the process must exit and restart: WT_PANIC: WiredTiger library panic
2020-12-28T13:21:21.731+0800 F –        [conn2624] Fatal Assertion 50853 at src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp 420
2020-12-28T13:21:21.731+0800 F –        [conn2624]

***aborting after fassert() failure

可以看到核心问题就是 Too many open files。经查阅相关资料，造成如下问题的原因就是Centos7给每个用户默认的同时打开文件的数值为1024，可通过如下配置文件查看：

ulimit -a

其中所有的参数均可修改，那么如何修改open files呢？
在此提供两种方法：
首先查看系统全局参数：

所以我们可以修改的最大值也是174198

具体修改方法一：
新建一个nofile.conf文件：

vi /etc/security/limits.d/nofile.conf