Tell me about the most challenging technical problem you faced during your work on the project.

One of the most challenging tasks was optimizing a high-load service that processed millions of requests per second. The problem was that due to frequent locks and resource contention, delays occurred and throughput dropped.

To solve this, it was necessary to:

• Profile CPU and memory using pprof.
• Identify bottlenecks in synchronization, replace mutexes with more efficient structures, such as atomic operations.
• Rewrite critical sections of code, minimizing locks.
• Use a goroutine pool to control the number of tasks running simultaneously.

As a result, delays were significantly reduced and the stability of the service was improved, positively impacting the user experience.