Load balancing is something most of us assume is a solved problem. But the idea that load balancing is "solved" could not be further from the truth. If you use multiple load balancers, the problem is even worse. Most of us use "random" or "round-robin" techniques, which have certain advantages but are highly inefficient. Others use more complex algorithms like "least-conns," which can be more efficient but have horrific edge cases. "Consistent hashing" is a very useful technique, but only applies to certain problems. There are several factors that exist both in theory and practice that make efficient load balancing an exceptionally hard problem. For instance:

• Poisson request arrival times 
• Exponentially distributed response latency 
• Oscillations when sharing data between multiple load balancers

We’ll talk about techniques and algorithms such as Randomized Least-conns, Join-Idle-Queue, and Load Interpretation. Load balancing perfectly may be impossible in the real world, but we can do better than “random,” “round-robin,” and naive “least-conns”.