Perguntas de entrevista de vagas de Senior Java Developer da empresa OSTTRA

Interview process was very fast and their were 3 technical rounds. I have no where seen that the HR tells that it is mangerial round and interviewer starts the call by saying 'are you ready for technical round' and when I told him that HR said it is mangerial he says that there are no managers in this company and all are technical people. I was not prepared for technical round. And OSTTRA is not a great brand that you need to take 3 tech rounds and no mangerial. First 2 rounds were good and friendly people took interviews, the last interviewer was asking way tough questions related to Threading, for example create your own permit( that we have in semaphore)? My 3rd round also went fine, but still I did not receive any call for further discussion. OSTTRA is IHS Markit, and I had same experience with IHS Markit too, if you give even one answer wring they dont take you. If I would have known they are same company would not have given interview rounds. Please understand everyone gives 1 or 2 wrong answers in an interview, it should not make a big deal when the person has already cleared 2 tech rounds of programming.