Can someone think of a way to find out where our rails production server hangs? Its CPU is at 99% so I assume it gets lost in a while/for/each loop. Unfortunately we can't find a candidate loop.
The problem does not occur in development and our test suit now has 100% code coverage.
We were already attaching to Ruby via gdb, but didn't know where to go from there.
Any ideas?
Once you have attached with gdb to the busy looping process then call rb_backtrace from gdb:
> call rb_backtrace()
The output from rb_backtrace will be similar to a crash report, and the output will go to your log files similar to a standard Ruby error backtrace.
From there you should hopefully already be a step closer to the solution since you will see where in your Ruby code the process is stuck.
You can check out some more tips here:
http://isotope11.com/blog/getting-a-ruby-backtrace-from-gnu-debugger
This is not a clean solution but at least the following resolved the problem for us: we migrated to the 'thin' webserver and removed 'devise'.
Related
I have a rails runner script I am attempting to debug. Currently I've got a bunch of puts statements showing me state/status but it's skipping a bunch of those statements and I don't know why. I want to debug and step through the lines and see what happens then.
I saw pry is one way to break out of execution but I don't know how to step in/out/over and examine variables.
I'm also a very big user of Jetbrains products and I figured I'd use the Rubymine debugger with breakpoints but it looks like it can only run vanilla ruby scripts, not rails runner scripts.
Suggestions? Thanks...
Here is the list of most popular debugging tools in ruby. You can use them. Personally, I recommend you to start from pry-byebug
Someone was nice enough to submit my question to Jetbrains and they were very helpful! Here's a screenshot of my debug config in my Windows environment:
https://lh3.googleusercontent.com/-AR_BBqCg9qI/WhToSayDLuI/AAAAAAAAfX4/FS5ujyLWKKg2sO5qa5kCWT5Rtz8Bf7H6wCL0BGAYYCw/h498/2017-11-21.png
And THIS is an answer that addresses my question!
I currently have a problem with a project.
it freezes before it shows the "Started GET ...." seems like it hits an infinite loop.
now i dont really have much experience with debuggers in ROR, can anyone recommend anything i can use to trace the exact origin of the problem. if i can get an error code somewhere then i might be able to fix it.
currently i am using webrick, i tried thin and it gave the exact same error.but i am willing to use anything to find the exact origin of this error.
it seems to be related to the project because all other projects works fine on my environment.
Take a look at the Rails guide on debugging.
Also try running the Rails console ("rails c"); if you can get to a command prompt at all that means that the issue is not in loading the Rails environment (e.g. a problem in application.rb) but is somewhere in the process of making a web request. If there's a failure it may give you a better error message.
I am getting up and running with Spree in production on a 256MB Slicehost slice with MySQL, Mongrel, and Nginx. I am getting this error every time I try to access any URL in the app:
SystemStackError (stack level too deep):
compass (0.8.17) lib/compass/app_integration/rails/action_controller.rb:7:in `process'
vendor/plugins/haml/rails/./lib/sass/plugin/rack.rb:44:in `call'
(Some more test url requests are in this pastie)
What are the advanced (but free and open source) debugging strategies/tools I should use while in production mode so I can do better at solving this problem?
It's slightly different each time depending on the controller. I have tried increasing my stack size, but that doesn't help because there's probably just some loop I can't find.
The question is, how do I get a more detailed report of the exact output while in production?
I am using Deprec and Capistrano to execute all server side commands. I am running a mongrel cluster of 3. The log files I see are:
current/log$ ls
development.log
testsite.com-error.log
mongrel.8000.log
mongrel.8001.log
mongrel.8002.log
mongrel.log
production.log
testsite.com-access.log
I'm just looking for some advanced debugging strategies/tools while in production mode so I can do better at solving this problem. Maybe some cap tasks for streaming/debugging (or conditionally break-pointing!) the production app (really, a staging app) locally (do people do that?), or something that spits out every single thing that executes in code?
Thanks
I'd check all of your gems and plugins and any other dependencies your application might have: I'd guess that you're missing something (or have the wrong version of something) and it's failing badly enough that it can't even spit out a can't find require message.
check your action controller. On line 7 is most likely where the loop occurs.
Seems you have initiated some endless recursion on line 7 of your controller. Check if you are calling the same method inside the method.
Today, for no reason, my rails(2.1.0) application is very slow or even not responding.
It happens intermittently.
So sometimes it works but again it doesn't work.
When it doesn't work, I can't even load 'script/console production'.
I want to know where it's stuck.
How do I load console step-by-step so that I can know which part causes the problem?
Thanks.
Sam
You could be running out of memory on your server and so the machine can't respond to you. If you are running mongrel then get monit onto it to limit the memory it can use and restart where necessary.
If you are using Passenger, try limiting the amount of instances, and if you have already done that look up a script that kills passenger instances when too big via a cron job.
If it's not a memory issue then I'd probably need more information.
If you are able, try temporarily removing all plugins/gems and see if the app will boot. One of those is likely the problem.
The script/console file contains this.
#!/usr/bin/env ruby
require File.dirname(__FILE__) + '/../config/boot'
require 'commands/console'
You can find the commands/console file here for Rails 2.1.
I recommend loading up irb and trying to load your app from there.
require 'config/boot'
If that works, then try stepping through the rest of the mentioned commands/console script to find out which part is the problem.
If the boot file won't load, take a look at that config/boot.rb file to see if you can determine which part isn't working. Good luck!
When all else fails, you should be able to use strace to debug what the script/application is actually doing. Note that this should only be one of the last resorts as it produces extremely verbose information (and also mostly limited to I/O actions).
Try using 'strace script/console production' for example
We are trying to update a Rails Server to release 5.1.
Server starts fine; but on the first request, goes completely dead; and has to be killed with signal 9.
Doesn't matter if its Puma or Webrick.
Doesn't matter if its 5.1.0 or 5.1.7
Doesn't matter if its development or production mode.
Eventually I saw the process size was 90GB and growing!
I've tried rbtrace, but struggled to get anything meaningful out of it.
I'm on osx, so strace isn't available, and I've struggled to get dtrace or dtruss to work, or produce anything meaningful.
So looking for a way to get this rails server to tell me what it's problem is....
Let me know what additional information is salient.
After quite a long process, I found a solution that didn't so much find the source of the issue, but provided a process to work around it.
First off, I used
rails app:update
And accepted all of the overwrites. Then using git, I walked through all of the removed code from my config file and returned just the required sections [like config/routes.rb, and ActionMailer config, for example].
Application then started right up, no issue.
This also led me to
http://railsdiff.org/5.0.7.2/5.1.0
Which is pretty critical for Rails upgrading. This is well worth consuming:
https://github.com/rails/rails/issues/31377#issuecomment-350422347