Horizontal Scaling Issues on Render with Custom Components - Anyone Experienced This?

Hello !

I’m facing significant challenges with horizontal scaling of my Streamlit application on Render when using custom components. The app works perfectly with vertical scaling (upgrading to higher RAM/CPU tiers), but horizontal scaling seems to break functionality.

  • Platform: Render.com
  • Streamlit version: 1.39
  • Custom components: using streamlit-aggrid, and a few custom React components
  • Current setup: Single instance (Pro tier - 4GB RAM, 2 CPU)

My App work fine on a single instance but as soon as Activate the auto scale option with multiple instances and load balancing, Custom components fail to load properly, ( WebSocket connections seem to break)

Current Workaround

Currently forced to use vertical scaling only (upgrading to higher tiers like Pro Plus - 8GB RAM), which works but is:

  • More expensive than horizontal scaling
  • Has hard limits on maximum resources
  • Not ideal for handling traffic spikes

Has anyone successfully implemented horizontal scaling on Render with custom components?

Are there known compatibility issues between Streamlit’s architecture and horizontal scaling on cloud platforms?

What alternatives have you used for a Streamlit apps with 20-50+ concurrent users ?
Should I consider migrating to a different platform (AWS ECS, GCP Cloud Run, etc.) for better horizontal scaling support?

Any insights, similar experiences, or alternative solutions would be greatly appreciated!