Have you had a high-load system? How many users were in the system?

Yes, I have experience working with high-load systems. For example, in one project, the system served several hundred thousand active users during peak hours.

To ensure stable operation under such load, the following approaches were used:

• Horizontal scaling of services
• Use of caching (Redis, Memcached)
• Load balancing
• Asynchronous task and message queue processing
• Monitoring and alerting for quick response to issues

The number of users and load always depends on the specific system and its architecture, but experience working with hundreds of thousands of users helps understand key challenges and methods to address them.