Python/Go Data Sync Utility Tool

We are looking for an expert in python/go or similar technologies to develop a process that would run in the background and sync data from clients server to google firebase cloud and vice versa using API. Understanding of and grabbing ideas from open source technologies and multi threaded, queue based process development experience is critical success factor for the project. The deliverable should target three different platform (Windows/Linux(deb and rmp)/Mac). So, the tool has to be developed in some technologies that would allow it to run on any of the above platform with just different packaging. Here is basic high level process flow attached. Drop us a note if you interested and explain any experience developing similar multi threaded performance optimized process in the past. Lets talk the details if you interested. Please answer the following question when you apply for this job: Q. When you pass data between multiple threads and how? Just explain in natural term..don't have to give code example.