# Rails 2.2: ActiveRecord in thread doesn't run if action has completed

**URL:** <https://www.ruby-forum.com/t/rails-2-2-activerecord-in-thread-doesnt-run-if-action-has-completed/151746>\
**Category:** Rails\
**Created:** [October 25, 2008, 1:09am UTC](https://www.ruby-forum.com/t/rails-2-2-activerecord-in-thread-doesnt-run-if-action-has-completed/151746 "2008-10-25T01:09:01Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![malesca](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/c89c15/32.png) [@malesca](https://www.ruby-forum.com/u/malesca)\
**Post date:** [October 25, 2008, 1:09am UTC](https://www.ruby-forum.com/t/rails-2-2-activerecord-in-thread-doesnt-run-if-action-has-completed/151746/1 "2008-10-25T01:09:01Z")

</div>

I have some callback code that submits data over the net, gets an id  
back and should write it to DB.

This takes a few seconds. I want to run it asynchronously, without  
slowing down the request/response cycle. I would like to avoid a  
worker/queue system if possible, to keep things simple.

I eventually want it in an observer, but I’m currently trying it out  
right in a controller. If I do this:

def some\_action  
…  
Thread.new {  
Thread.abort\_on\_exception = true  
logger.debug “!! 1”  
sleep 5  
logger.debug “!! 2”  
sleep 5  
logger.debug “!! Posts: #{Post.count}”  
sleep 5  
logger.debug “!! 3”  
}  
render :text =\> “foo”  
end

Then visiting that page will log 1 and 2, but nothing else. 2 can log  
after the action completes:

Completed in 4734ms (View: 4619, DB: 36) | 200 OK [http://  
mysite.dev/]  
!! 2

If the thread is this instead:

```
Thread.new {
  Thread.abort_on_exception = true
  logger.debug "!! 1"
  logger.debug "!! 2"
  logger.debug "!! Posts: #{Post.count}"
  sleep 10
  logger.debug "!! 3"
}

```

so Post.count runs before the action completes, then it works fine,  
and 3 can output after the action completes:

…  
!! Posts: 33  
…  
Completed in 5078ms (View: 4940, DB: 29) | 200 OK [http://  
mysite.dev/]  
!! 3

So basically, it seems that a thread in a controller action can run  
after the action completes, but ActiveRecord can’t.

Is this an inherent limitation? Can I configure my way around it? I  
was hoping 2.2 connection pools would mean this would work, but I  
guess not.

I’ve looked at [GitHub - imedo/background: deprecated - Please use successor project background\_lite](http://github.com/imedo/background) and  
[GitHub - tra/spawn: Placeholder for the repo previously known as spawn](http://github.com/tra/spawn)  
but had issues with both, so I thought I’d try to figure it out with a  
simple Thread for now.

---

<div class="post-metadata">

**Author:** ![malesca](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/c89c15/32.png) [@malesca](https://www.ruby-forum.com/u/malesca)\
**Post date:** [October 25, 2008, 9:24am UTC](https://www.ruby-forum.com/t/rails-2-2-activerecord-in-thread-doesnt-run-if-action-has-completed/151746/2 "2008-10-25T09:24:10Z")

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On Oct 25, 9:19 am, Henrik N [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Aha! Changing  
> config.cache\_classes = true  
> to  
> config.cache\_classes = false  
> in config/environments/development.rb fixed this.

Oops. The other way around, of course. Changing from false to true.

---

<div class="post-metadata">

**Author:** ![malesca](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/c89c15/32.png) [@malesca](https://www.ruby-forum.com/u/malesca)\
**Post date:** [October 25, 2008, 9:20am UTC](https://www.ruby-forum.com/t/rails-2-2-activerecord-in-thread-doesnt-run-if-action-has-completed/151746/3 "2008-10-25T09:20:04Z")

</div>

On Oct 25, 1:08 am, Henrik N [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> So basically, it seems that a thread in a controller action can run  
> after the action completes, but ActiveRecord can’t.
> 
> Is this an inherent limitation? Can I configure my way around it? I  
> was hoping 2.2 connection pools would mean this would work, but I  
> guess not.

Aha! Changing  
config.cache\_classes = true  
to  
config.cache\_classes = false  
in config/environments/development.rb fixed this. So I expect the  
class was reloaded, messing up the connection.