rails app hangs when redirect to .pdf url with wicked_pdf middle wear, but generates the pdf file in /tmp after system time out

Question

the problem: both my prod and dev environment is using nginx and unicorn, i am trying to use wicked_pdf gem to generate a pdf version of my user list page, it is working in the dev environment. however in production, the request kept timing out and i noticed that before it's timing out, the pdf file will appear in /tmp folder with size 0, however, right after the timeout (unicorn process is killed) the pdf will finish rendering, but it's not being displayed on the browser. In my dev environment, the file will be removed from /tmp folder and displayed in browser. the dev and production env are the same for the files involved (to my knowledge)

the setup added the following line in the respective files:

Gemfile: gem 'wkhtmltopdf-binary', '~> 0.9.9.3' gem 'wicked_pdf'

config/mime_types.rb Mime::Type.register "application/pdf", :pdf

config/application.rb config.middleware.use WickedPdf::Middleware

controller: redirect_to "/t24_user/t24_to_ad_user.pdf"

i suspect this could be some deadlock issue, however, i can't seem to find any logs other than:

unicorn.stderr.log, and there is no err in the production.log file:

  E, [2020-07-10T17:55:23.889910 #31607] ERROR -- : worker=1 PID:31617 timeout (46s > 45s), killing
  E, [2020-07-10T17:55:23.901877 #31607] ERROR -- : reaped #<Process::Status: pid 31617 SIGKILL (signal 9)> worker=1
  I, [2020-07-10T17:55:23.902035 #31607]  INFO -- : worker=1 spawning...
  I, [2020-07-10T17:55:23.905433 #39297]  INFO -- : worker=1 spawned pid=39297
  I, [2020-07-10T17:55:23.905655 #39297]  INFO -- : worker=1 ready

any help would be appreciated.

zinovyev zinovyev · Accepted Answer · 2020-07-10T23:00:09

Try to monitor the usage of the resources of your service by running top in the separate terminal window while trying to upload the pdf file. It may happen that you're just out of MEM =)

BTW, which distro do you use on production and which one locally? The difference in their libs may cause the error too.. As far, as i remember I used to have some issues with Apline once, while this gem was working fine on Ubuntu.

rails app hangs when redirect to .pdf url with wicked_pdf middle wear, but generates the pdf file in /tmp after system time out

1 Answers