heroku unicorn timeout doesn't work when downloading files

Question

I'm running a rails 4 app on Heroku with Unicorn.

This app creates a fairly large xls file

To give it enough time, I increased the timeout via config/unicorn.rb:

timeout 240

This doesn't work when I run the page generating the xls file, a timeout occurs after 3001ms.

Why?

This is my log:

2014-04-29T13:43:27.323190+00:00 app[web.1]: I, [2014-04-29T13:43:27.323084 #8]  INFO -- : Started GET "/live_sales.xls?action=index&controller=live_sales" for 81.244.45.218 at 2014-04-29 13:43:27 +0000
2014-04-29T13:43:27.340252+00:00 app[web.1]: D, [2014-04-29T13:43:27.340190 #8] DEBUG -- : logged in? true
2014-04-29T13:43:27.339294+00:00 app[web.1]: I, [2014-04-29T13:43:27.339181 #8]  INFO -- : Processing by LiveSalesController#index as XLS
2014-04-29T13:43:27.345465+00:00 app[web.1]: D, [2014-04-29T13:43:27.345383 #8] DEBUG -- :   ItemRef Load (3.1ms)  SELECT gamme FROM "item_refs" WHERE (gamme is not null and gamme <> '') GROUP BY gamme
2014-04-29T13:43:28.577687+00:00 app[web.1]: D, [2014-04-29T13:43:28.577526 #8] DEBUG -- :   LiveSale Load (1210.0ms)  SELECT invoice_date, item_refs.item_brand, item_refs.item_label, item_refs.gamme, item_refs.sub_gamme, item_refs.id, item_refs.item_reference, item_refs.date_published, item_refs.date_unpublished, item_refs.price_purchase, item_refs.current_stock, item_refs.item_published,
2014-04-29T13:43:28.577694+00:00 app[web.1]:  sum(price_purchase * current_stock) as stock_value,sum(quantity) as quantity,
2014-04-29T13:43:28.577697+00:00 app[web.1]:  sum(price_purchase * quantity) as total_purchase FROM "live_sales" left join item_refs on item_refs.id = live_sales.item_ref_id and item_refs.item_published is true and item_refs.disabled is false WHERE ((invoice_date between '2014-03-29 13:43:27 +0000' and '2014-04-29 13:43:27 +0000')) GROUP BY invoice_date, item_refs.item_brand, item_refs.item_label, item_refs.gamme, item_refs.sub_gamme, item_refs.id, item_refs.item_reference, item_refs.date_published, item_refs.date_unpublished, item_refs.price_purchase, item_refs.current_stock, item_refs.item_published ORDER BY invoice_date asc, 
2014-04-29T13:43:57.331088+00:00 heroku[router]: at=error code=H12 desc="Request timeout" method=GET path=/live_sales.xls?action=index&controller=live_sales host=azzanalytics.herokuapp.com request_id=6e67b74e-3db8-4853-b5c6-c1f884eaa31e fwd="81.244.45.218" dyno=web.1 connect=1ms service=30001ms status=503 bytes=0

Thanks!

Answer 1

the suggestion is: use a background process!

there is no way around it! it is a best practice in web-apps to return to the client as fast as possible, because it frees up resources. when you have just one dyno running at heroku and you have multiple requests, they will get blocked for your timeout and no user is able to access your page. you can easily have denial of service cases when you have such longrunning processes. heroku timed out at 30 second regardless of you override it on your thin server

in case you do not want to do background processes because of the cost, have a look at freemium: https://github.com/phoet/freemium or delayed_job