这次排错过程主要是思路，视野打开后会觉得豁然开朗，原来这其实是个小问题[尴尬]。

1、没注重应用启动的各服务及其用途，只会简单查看 status；

2、看到错误第一时间想到的是 Baidu（没其他意思），找找 logpath 先看日志不好吗？

3、未认识到服务之间的关联关系（比如 postgresql 与 unicorn 之间），前面一直知道 unicorn 启动后没正常监听到端口，但是日志并没啥特别信息（嗯，可能是因为看错了文件）[苦笑]

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二、排错过程

1、启动 unicorn 未监听端口

日志路径 :   /var/log/gitlab/unicorn/unicorn_stderr.log

PG::ConnectionBad: could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/var/opt/gitlab/postgresql/.s.PGSQL.5432"? /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `initialize' /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `new' /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:651:in `connect' /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:242:in `initialize' /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `new' /opt/gitlab/embedded/lib/ruby/gems/2.3.0/gems/activerecord-4.2.10/lib/active_record/connection_adapters/postgresql_adapter.rb:44:in `postgresql_connection' ··· ··· ··· ···

信息显示是因为连不上PG，所以启动 postgresql 后重启即可正常（嗯，是酱）。。

2、postgresql down

down: postgresql: 0s, normally up, want up; run: log: (pid 623) 15816094s 

通过 PG 的日志路径 ： /var/log/gitlab/postgresql/current 可以查看到如下信息

2018-11-01_08:18:09.49669 FATAL: could not map anonymous shared memory: Cannot allocate memory 2018-11-01_08:18:09.49671 HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory, swap space, or huge pages. To reduce the request size (currently 4292984832 bytes), reduce PostgreSQL's shared memory usage, perhaps by reducing shared_buffers or max_connections. 2018-11-01_08:18:09.49671 LOG: database system is shut down

也可以通过命令 `gitlab-ctl tail postgresql`，得到一样的信息，于是可以确定问题。。

This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory, swap space, or huge pages. To reduce the request size (currently 4292984832 bytes), reduce PostgreSQL's shared memory usage, perhaps by reducing shared_buffers or max_connections. 2018-11-01_07:52:06.63024 LOG: database system is shut down

于是在配置文件中对 postgresql 的 shared_buffers 和 max_connections 两项进行了限制

[root@V2 ~]# cat /etc/gitlab/gitlab.rb |grep -v ^$ |grep -v ^# external_url 'http://xxx.xxx.xxx.xxx.xxx:8090' unicorn['worker_timeout'] = 60 unicorn['worker_processes'] = 3 unicorn['listen'] = 'xxx.xxx.xxx.xxx.xxx' unicorn['port'] = 8870 postgresql['enable'] = true postgresql['data_dir'] = "/var/opt/gitlab/postgresql/data" postgresql['shared_buffers'] = "256MB" # ! **recommend value is 1/4 of total RAM, up to 14GB.** postgresql['max_connections'] = 200 nginx['listen_addresses'] = ['*'] nginx['listen_port'] = 8090

配置完成保存，之后更新配置，重启应用即可。

gitlab-ctl reconfigure # 更新配置 gitlab-ctl restart # 重启应用 gitlab-ctl status # 查看服务状态

参考资料

1. 502-Whoops, GitLab is taking too much time to respond

2. gitlab安装以及安装过程中遇到的问题

3. Postgresql down

4. centos7安装部署gitlab服务器

5. 我所遇到的GitLab 502问题的解决

6. HTTP 502: Whoops, GitLab is taking too much time to respond. Even after Server restart