Technical recruiter contacted me and offered amazing job with IHS Markit company. After prescreen interview (around 15 min) I received an offline assessment. The task was: “In a concurrent environment, one job is building (expanding) a tree data structure, where all other jobs are dumping periodically the current number of nodes. Use any language or technology to solve the task.” After implementing the task they invited me to face to face interview. At the first part of the interview they described briefly current project and what the tasks they have in general. In the second part of the interview they reviewed your assignment. They didn't look at it before and they tried to understand how it was implemented on the fly. They didn't compile and launch it at all. When you implement this task simply create a single thread that builds a tree and few more which counts the current amount of nodes. I implemented it in a bit more complex way and got negative feedback for this complexity. After reviewing your code they showed few examples of concurrent code and asked what is wrong if multiple threads access this method. So it's nice to refresh your knowledge in concurrency - especially fail fast iterators and concurrent hash maps. That was it for this interview. After I heard nothing from them.