How much memory does JATOS need?

Comments

• kri

  November 2021 edited November 2021

  Hi Ethan,

  Yes, the blog post you mention is quite old and it's on my list to write a new version of it - but my list is pretty long ...

  And it's difficult to say: there are many factors that come to play, e.g.

  • Number of users and studies
  • Number of participants that run a study in parallel
  • Do you have an extra MySQL database and do you have it installed on the same server?
  • Size of the result data or result files that are send by the studies
  • Size of the files loaded by the studies

  But as a rule of thumb:

  1. 1 GB is only enough for a small JATOS that is not used heavily. Maybe for one experiment with not many participants in parallel and the experiment doesn't use much resources. Don't use MySQL.
  2. 4 GB for a group of users with a couple of studies (2 GB can be enough if you have the database on a different host).
  3. 8 GB for a bigger installation with hundreds of users and many studies that run in parallel.

  And as an example for a bigger installation that I'm handling:

  • DigitalOcean 'Basic Droplet' with 8 GB RAM, 4 CPUs
  • An MySQL is installed on the same server sharing all resources with JATOS
  • JATOS memory usage is limited to 3 GB (-J-Xmx3G)
  • I added an extra volume for all data (MySQL's data files and JATOS' study assets, study logs, result uploads)
  • Nginx is doing the encryption together with certbot
  • More info: https://github.com/kristian-lange/ESCoP-JATOS-setup

  I hope this helps!

  Kristian
• ethanweed

  November 2021

  Thank you Kristian, this is hugely helpful, and confirms my suspicions about the trouble we’ve been having. We’ve moved to a machine with 2 GB of RAM, and so far so good, but we should probably consider something beefier in the future. Thanks so much for this full answer.