2016-06-08 02:40:38 +00:00
|
|
|
# Debugging Tips
|
|
|
|
|
|
|
|
Sometimes things don't work the way they should. Here are some tips on debugging issues out
|
|
|
|
in production.
|
|
|
|
|
2016-07-01 15:18:33 +00:00
|
|
|
## Mail not working
|
2016-06-08 02:40:38 +00:00
|
|
|
|
2016-07-01 15:18:33 +00:00
|
|
|
A common problem is that mails are not being sent for some reason. Suppose you configured
|
|
|
|
an SMTP server, but you're not seeing mail delivered. Here's how to check the settings:
|
|
|
|
|
|
|
|
1. Run a Rails console:
|
|
|
|
|
|
|
|
```sh
|
|
|
|
sudo gitlab-rails console production
|
|
|
|
```
|
|
|
|
|
|
|
|
or for source installs:
|
|
|
|
|
|
|
|
```sh
|
|
|
|
bundle exec rails console production
|
|
|
|
```
|
|
|
|
|
2018-11-13 00:39:21 +00:00
|
|
|
1. Look at the ActionMailer `delivery_method` to make sure it matches what you
|
2016-07-01 15:18:33 +00:00
|
|
|
intended. If you configured SMTP, it should say `:smtp`. If you're using
|
|
|
|
Sendmail, it should say `:sendmail`:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
irb(main):001:0> ActionMailer::Base.delivery_method
|
|
|
|
=> :smtp
|
|
|
|
```
|
|
|
|
|
2018-11-13 00:39:21 +00:00
|
|
|
1. If you're using SMTP, check the mail settings:
|
2016-07-01 15:18:33 +00:00
|
|
|
|
|
|
|
```ruby
|
|
|
|
irb(main):002:0> ActionMailer::Base.smtp_settings
|
|
|
|
=> {:address=>"localhost", :port=>25, :domain=>"localhost.localdomain", :user_name=>nil, :password=>nil, :authentication=>nil, :enable_starttls_auto=>true}```
|
|
|
|
```
|
|
|
|
|
|
|
|
In the example above, the SMTP server is configured for the local machine. If this is intended, you may need to check your local mail
|
|
|
|
logs (e.g. `/var/log/mail.log`) for more details.
|
|
|
|
|
2018-11-13 00:39:21 +00:00
|
|
|
1. Send a test message via the console.
|
2016-07-01 15:18:33 +00:00
|
|
|
|
|
|
|
```ruby
|
|
|
|
irb(main):003:0> Notify.test_email('youremail@email.com', 'Hello World', 'This is a test message').deliver_now
|
|
|
|
```
|
|
|
|
|
|
|
|
If you do not receive an e-mail and/or see an error message, then check
|
|
|
|
your mail server settings.
|
|
|
|
|
|
|
|
## Advanced Issues
|
|
|
|
|
|
|
|
For more advanced issues, `gdb` is a must-have tool for debugging issues.
|
|
|
|
|
|
|
|
### The GNU Project Debugger (gdb)
|
|
|
|
|
|
|
|
To install on Ubuntu/Debian:
|
2016-06-08 02:40:38 +00:00
|
|
|
|
|
|
|
```
|
|
|
|
sudo apt-get install gdb
|
|
|
|
```
|
|
|
|
|
|
|
|
On CentOS:
|
|
|
|
|
|
|
|
```
|
|
|
|
sudo yum install gdb
|
|
|
|
```
|
|
|
|
|
2018-07-25 05:15:52 +00:00
|
|
|
### rbtrace
|
|
|
|
|
|
|
|
GitLab 11.2 ships with [rbtrace](https://github.com/tmm1/rbtrace), which
|
|
|
|
allows you to trace Ruby code, view all running threads, take memory dumps,
|
|
|
|
and more. However, this is not enabled by default. To enable it, define the
|
|
|
|
`ENABLE_RBTRACE` variable to the environment. For example, in Omnibus:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
gitlab_rails['env'] = {"ENABLE_RBTRACE" => "1"}
|
|
|
|
```
|
|
|
|
|
2018-07-29 01:12:34 +00:00
|
|
|
Then reconfigure the system and restart Unicorn and Sidekiq. To run this
|
|
|
|
in Omnibus, run as root:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
/opt/gitlab/embedded/bin/ruby /opt/gitlab/embedded/bin/rbtrace
|
|
|
|
```
|
2018-07-25 05:15:52 +00:00
|
|
|
|
2016-06-08 02:40:38 +00:00
|
|
|
## Common Problems
|
|
|
|
|
|
|
|
Many of the tips to diagnose issues below apply to many different situations. We'll use one
|
|
|
|
concrete example to illustrate what you can do to learn what is going wrong.
|
|
|
|
|
|
|
|
### 502 Gateway Timeout after unicorn spins at 100% CPU
|
|
|
|
|
|
|
|
This error occurs when the Web server times out (default: 60 s) after not
|
|
|
|
hearing back from the unicorn worker. If the CPU spins to 100% while this in
|
|
|
|
progress, there may be something taking longer than it should.
|
|
|
|
|
|
|
|
To fix this issue, we first need to figure out what is happening. The
|
|
|
|
following tips are only recommended if you do NOT mind users being affected by
|
|
|
|
downtime. Otherwise skip to the next section.
|
|
|
|
|
|
|
|
1. Load the problematic URL
|
|
|
|
1. Run `sudo gdb -p <PID>` to attach to the unicorn process.
|
|
|
|
1. In the gdb window, type:
|
|
|
|
|
|
|
|
```
|
|
|
|
call (void) rb_backtrace()
|
|
|
|
```
|
|
|
|
|
|
|
|
1. This forces the process to generate a Ruby backtrace. Check
|
|
|
|
`/var/log/gitlab/unicorn/unicorn_stderr.log` for the backtace. For example, you may see:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:33:in `block in start'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:33:in `loop'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:36:in `block (2 levels) in start'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:44:in `sample'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:68:in `sample_objects'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:68:in `each_with_object'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:68:in `each'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:69:in `block in sample_objects'
|
|
|
|
from /opt/gitlab/embedded/service/gitlab-rails/lib/gitlab/metrics/sampler.rb:69:in `name'
|
|
|
|
```
|
|
|
|
|
|
|
|
1. To see the current threads, run:
|
|
|
|
|
|
|
|
```
|
2016-11-01 23:59:32 +00:00
|
|
|
thread apply all bt
|
2016-06-08 02:40:38 +00:00
|
|
|
```
|
|
|
|
|
|
|
|
1. Once you're done debugging with `gdb`, be sure to detach from the process and exit:
|
|
|
|
|
|
|
|
```
|
|
|
|
detach
|
|
|
|
exit
|
|
|
|
```
|
|
|
|
|
|
|
|
Note that if the unicorn process terminates before you are able to run these
|
|
|
|
commands, gdb will report an error. To buy more time, you can always raise the
|
|
|
|
Unicorn timeout. For omnibus users, you can edit `/etc/gitlab/gitlab.rb` and
|
|
|
|
increase it from 60 seconds to 300:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
unicorn['worker_timeout'] = 300
|
|
|
|
```
|
|
|
|
|
|
|
|
For source installations, edit `config/unicorn.rb`.
|
|
|
|
|
|
|
|
[Reconfigure] GitLab for the changes to take effect.
|
|
|
|
|
|
|
|
[Reconfigure]: ../restart_gitlab.md#omnibus-gitlab-reconfigure
|
|
|
|
|
|
|
|
#### Troubleshooting without affecting other users
|
|
|
|
|
|
|
|
The previous section attached to a running unicorn process, and this may have
|
|
|
|
undesirable effects for users trying to access GitLab during this time. If you
|
|
|
|
are concerned about affecting others during a production system, you can run a
|
|
|
|
separate Rails process to debug the issue:
|
|
|
|
|
|
|
|
1. Log in to your GitLab account.
|
|
|
|
1. Copy the URL that is causing problems (e.g. https://gitlab.com/ABC).
|
2017-10-12 08:21:16 +00:00
|
|
|
1. Create a Personal Access Token for your user (Profile Settings -> Access Tokens).
|
2016-06-08 02:40:38 +00:00
|
|
|
1. Bring up the GitLab Rails console. For omnibus users, run:
|
|
|
|
|
2016-10-11 05:33:55 +00:00
|
|
|
```
|
2016-06-08 02:40:38 +00:00
|
|
|
sudo gitlab-rails console
|
|
|
|
```
|
|
|
|
|
|
|
|
1. At the Rails console, run:
|
|
|
|
|
|
|
|
```ruby
|
2016-10-11 05:33:55 +00:00
|
|
|
[1] pry(main)> app.get '<URL FROM STEP 2>/?private_token=<TOKEN FROM STEP 3>'
|
2016-06-08 02:40:38 +00:00
|
|
|
```
|
|
|
|
|
|
|
|
For example:
|
|
|
|
|
|
|
|
```ruby
|
|
|
|
[1] pry(main)> app.get 'https://gitlab.com/gitlab-org/gitlab-ce/issues/1?private_token=123456'
|
|
|
|
```
|
|
|
|
|
|
|
|
1. In a new window, run `top`. It should show this ruby process using 100% CPU. Write down the PID.
|
|
|
|
1. Follow step 2 from the previous section on using gdb.
|
|
|
|
|
2017-11-11 01:14:54 +00:00
|
|
|
### GitLab: API is not accessible
|
|
|
|
|
|
|
|
This often occurs when gitlab-shell attempts to request authorization via the
|
|
|
|
internal API (e.g., `http://localhost:8080/api/v4/internal/allowed`), and
|
|
|
|
something in the check fails. There are many reasons why this may happen:
|
|
|
|
|
|
|
|
1. Timeout connecting to a database (e.g., PostgreSQL or Redis)
|
|
|
|
1. Error in Git hooks or push rules
|
|
|
|
1. Error accessing the repository (e.g., stale NFS handles)
|
|
|
|
|
|
|
|
To diagnose this problem, try to reproduce the problem and then see if there
|
|
|
|
is a unicorn worker that is spinning via `top`. Try to use the `gdb`
|
|
|
|
techniques above. In addition, using `strace` may help isolate issues:
|
|
|
|
|
|
|
|
```shell
|
|
|
|
strace -tt -T -f -s 1024 -p <PID of unicorn worker> -o /tmp/unicorn.txt
|
|
|
|
```
|
|
|
|
|
|
|
|
If you cannot isolate which Unicorn worker is the issue, try to run `strace`
|
|
|
|
on all the Unicorn workers to see where the `/internal/allowed` endpoint gets
|
|
|
|
stuck:
|
|
|
|
|
|
|
|
```shell
|
|
|
|
ps auwx | grep unicorn | awk '{ print " -p " $2}' | xargs strace -tt -T -f -s 1024 -o /tmp/unicorn.txt
|
|
|
|
```
|
|
|
|
|
|
|
|
The output in `/tmp/unicorn.txt` may help diagnose the root cause.
|
|
|
|
|
2016-06-08 02:40:38 +00:00
|
|
|
# More information
|
|
|
|
|
|
|
|
* [Debugging Stuck Ruby Processes](https://blog.newrelic.com/2013/04/29/debugging-stuck-ruby-processes-what-to-do-before-you-kill-9/)
|
|
|
|
* [Cheatsheet of using gdb and ruby processes](gdb-stuck-ruby.txt)
|